Rheumatoid Factor: The Most Remarkable Autoantibody in Rheumatoid Arthritis
Rheumatoid Factor: The Most Remarkable Autoantibody in Rheumatoid Arthritis
Rheumatoid Factor:
The Most Remarkable Autoantibody in Rheumatoid Arthritis
Celebrating World Arthritis Day (WAD)
Rheumatoid Factor: The Most Remarkable Autoantibody in Rheumatoid Arthritis
World Arthritis Day (WAD) is celebrated on 12th October to help raise global awareness of the existence and impact of rheumatic and musculoskeletal diseases (RMDs). It is estimated that over one-hundred million people are currently undiagnosed impacting their quality of life and participation in society – including their ability to work and lead a normal life. As a result this increases dependency on state welfare, the healthcare system and the required support from their family and friends.
The European League Against Rheumatism (EULAR) launched the ‘Don’t Delay, Connect Today’ campaign focusing on the importance of early diagnosis and access to care.
Randox Reagents fully supports the importance of early diagnosis – to aid in the early implementation of effective treatment plans, aiding in improved health outcomes – it’s the ethos of our business. This blog delves deeper into rheumatoid factor (RF), the most remarkable autoantibody in rheumatoid arthritis.
Pathobiology of Rheumatoid Arthritis (RA)
The pathophysiology of RA involves various signaling pathways and immune modulators (effector cells and cytokines) as indicated in figure 1. Joint destruction is caused by the intricate interactions of immune modulators, beginning at the synovial membrane and encompassing most IA structures, with synovitis caused by both or individually, the local activation or influx of mononuclear cells, including: B cells, T cells, dendritic cells, plasma cells, mast cells and macrophages. Consequently, “the synovial lining becomes hyperplastic, and the synovial membrane expands and forms villi”. The neutrophils, chondrocytes and synoviocytes secrete enzymes that degrades the cartilage in the joint whereas the osteoclast-rich area of the synovial membrane destroys the bone 4.
Rheumatoid arthritis (RA), “the most common systemic inflammatory autoimmune disease” affecting 1% of the global population, is characterised by fatigue, synovial joint pain, stiffness, swelling and destruction, with severe symptoms resulting in disability. Whilst the exact cause of RA is unknown, it is believed that genetic and environmental factors play a role in triggering the disease 2, 3. Differences in the human leukocyte antigen (HLA)-DRB1 alleles (proteins with a critical role in the immune system) have been identified as a genetic variant for RA, observed in >80% of patients, particularly in those testing positive for RF. Moreover, those with variations in the HLA-DRB1 who smoke, increase their risk of RA. As RA is more common in women (2-fold increased risk in women compared to men), hormonal influences are an area of active research, however, an inverse correlation with breastfeeding has been identified. Women who breastfeed for >13 months aids in reducing the risk of RA compared to women who have never breastfed 3, 4.
Figure 1: Schematic view of (a) a normal joint and (b) a joint affected by RA 4
Clinical Significance of Rheumatoid Factor (RF)
Interestingly, elevated levels of RF have been observed in other autoimmune conditions such as Sjögren syndrome and systemic lupus erythematosus (SLE) as well as non-autoimmune conditions including old age and chronic infections. Despite this, RF in RA patients can be distinguished from RF in healthy individuals. RF in RA patients displays affinity maturation whereas RF in healthy individuals has low affinity and are polyreactive 2.
RF is a class of immunoglobulin (Ig) autoantibodies that are directed against the fragment crystallizable region (Fc region), the tail region of the IgG antibody. In RA, RF are produced by the B cells present in lymphoid follicles and the germinal center(GC)-like structures that mature in inflamed synovium. Most RF are IgM antibodies, but may also be IgG or IgA isoforms. IgM RF are detected in 60% to 80% of RA patients. “RF testing in RA patients has a sensitivity of 60% to 90% and a specificity of 85%” (5). RF is a highly valuable biomarker in RA 5, 2.
Key Features of the Randox Rheumatoid Factor Assay
The Randox automated latex enhanced immunoturbidimetric rheumatoid factor assay provides an accurate assessment of RF titre as the Randox rheumatoid factor calibrator is standardised against the primary WHO material, 1st British Standard 64/2. With a wide measuring range of 6.72 – 104lU/ml for the comfortable detection of clinically important results, the Randox RF assay is available in a liquid ready-to-use format for the comfortable detection of clinically important results. The Randox rheumatoid factor assay does not suffer from interference from C1q complement and is stable until expiry date. With dedicated calibrator and controls for a complete testing package, Randox offer applications, detailing instrument-specific settings for the convenient use of the Randox rheumatoid factor assay on a wide range of clinical chemistry analysers.
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Randox Reagents Homepage
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Specific Proteins Panel
Alzheimer’s Disease: The Role of Apolipoprotein E
Alzheimer’s Disease: The Role of Apolipoprotein E
Raising awareness of Alzheimer’s Disease
Every year we celebrate Alzheimer’s Day on 21st September to help raise awareness around dementia. Dementia is the medical name attributed to a set of symptoms affecting the brain, including: difficulties with problem solving, thinking, language and memory loss. AD is the most common form of dementia accounting for 60 – 80% of cases and it is believed that half of patients with Alzheimer’s dementia (dementia due to AD) have Alzheimer’s disease 1, 2.
About Alzheimer’s Disease (AD)
AD is one of the most devastating and complex diseases characterised by:
- Neurodegeneration resulting in memory loss 2
- Neurofibrillary tangles composed of tau amyloid fibrils which associates with synapse loss 2
- Accumulation of β-amyloid (Aβ) plaques 2
- Other cognitive functions 2
Figure 1: Alzheimer’s Disease Demographic, 2019 3
It is believed that AD is expected to begin 20 years prior to symptom onset, as the small changes in the functioning of the brain are unnoticeable to the person affected. Overtime, the symptoms progress and begin to interfere with the patient’s ability to perform everyday tasks. The final stages of AD leaves the patient bed-bound, requiring 24/7 care. Ultimately, AD is fatal. Age has been identified as a risk factor for AD with 10% of people over the age of 65 affected. Moreover, AD has been recognised as a leading cause of morbidity and the sixth leading cause of mortality, but the fifth leading cause of death in over 65’s in the US .3
Physiological Significance of Apolipoprotein E
Apolipoprotein E (Apo E) is a lipoprotein composed of 299 amino acids with a molecular weight of 34kDa. Apo E is responsible for the regulation of homeostasis through the mediation of lipid transport from and to bodily cells and tissues. Apo E comprises of three common isoforms: apo E2, apo E3 and apo E4. The apo E isoforms differ due to differences in either the 112 and 158 amino acids, whether either arginine (ARG) or cysteine (CYS) is present 4.
Apo E3 is the parent form of apo E and is responsible for the clearance of triglyceride-rich lipoproteins. Apo E3 is associated with normal lipid plasma concentrations. Apo E2 is the rarest of the apo E isoforms and differs slightly compared to the apo E3 isoform through the substitution of a single amino acid, ARG158Cys, located near the low-density lipoprotein receptor (LDLR) recognition site.
Apo E2 displays impaired binding to the receptor, prohibiting the clearance of triglyceride-rich lipoprotein remnant particles. Apo E2 is strongly associated with type-III hyperlipoproteinemia. Apo E3 also differs from apo E4, again through the substitution of a single amino acid, Cys112Arg. The main difference between apo E3 and apo E4 is that apo E4 is unaffected by the binding of the isoform to LDLR. However, apo E4 is strongly associated with dyslipidemia 5. Fig. 2 provides a visual representation of the variations in the Apo E isoforms.
Figure 2: Variations in the Apo E Isoforms 4
Apo E is expressed in numerous bodily organs with the liver presenting with the highest expression followed by the brain. Astrocytes and, to a lesser extent, microglia are the major cells responsible for the expression of apo E in the brain. In the brain, apo E, apo J and apo A-1 are predominantly expressed on distinct high-density-like lipoprotein particles. Whilst apo A-1 is the major apolipoprotein of high-density lipoproteins (HDL), in the central nervous system (CNS), apo E is the predominant apolipoprotein of HDL-like lipoproteins. HDL-like lipoproteins are the only lipoproteins present in the CNS. It is believed that the cholesterol released from apo E supports synaptogenesis 6.
Clinical Significance of Apolipoprotein E in Alzheimer’s Disease
Whilst apo E3 is the most abundant of the three isoforms, apo E4 has been known for decades to be the most significant genetic risk factor for late-onset AD. Inheriting the one copy of the apo E4 gene increases the risk of AD 2-3-fold, whilst inheriting two copies increases the risk of AD up to 12-fold 7. Whilst the underlying mechanism of apo E’s contribution to AD risk is still unclear and debatable, apo E has been identified as promoting amyloid β (Aβ) deposition and clearance as well as neurofibrillary tangles in the brain. Interestingly, Aβ-independent pathways exist for apo E in AD, which led to the unearthing of the new roles of apo E including the most recent, iron metabolism and mitochondria dysfunction 8, 9. Captivatingly, sex-related hormones may play a role in AD in apo E4 carriers as AD has been recognised to be more pronounced in women 10. Apo E4 has also been identified as impairing lipid transport, microglial responsiveness, glucose metabolism, synaptic plasticity and integrity, and cerebrovascular function and integrity. Some of these pathogeneses are independent of Aβ pathways. Furthermore, therapeutic strategies are aiming to modulate the quantity, lipidation, structural properties, Aβ interaction and receptor expression of Apo E 11.
Key Features of the Randox Apolipoprotein E Assay
Randox are one of the only manufacturers to offer the apo E assay in an automated clinical chemistry format. Utilising the immunoturbidimetric method, the Randox apo E assay is available in a liquid ready-to-use format. Not only does the Randox apo E suffer from limited interferences from bilirubin, haemoglobin, intralipid® and triglycerides for truly accurate results, it has an excellent measuring range of 1.04 – 12.3mg/dl for the comfortable detection of clinically important results. Moreover, apolipoprotein calibrator and controls are available for a complete testing package. Applications are available detailing instrument-specific settings for the convenient use of the Randox apo E assay on a wide range of clinical chemistry analysers.
Biochip Technology – Alzheimer’s Array
Utilising the Biochip Technology, Randox have developed an array to identify the risk of Alzheimer’s disease in just 3 hours with one effective test. In addition to a rapid and accurate diagnosis, this also introduces both cost and time-saving benefits. The apo E4 array is a research use only product developed for the Evidence Investigator, a semi-automated benchtop immunoassay analyser which can process up to 2376 test per hour as well as up to 44 analytes screened per biochip. The apo E4 array measures both total apo E protein levels and apo E4 protein levels directly from plasma samples as well as using a ratio, it can classify patients as negative or positive for apo E4. In turn, we can then assess their risk for the development of Alzheimer’s disease.
Related Products
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References
[1] Alzheimer’s Society. Alzheimer’s disease. [Online] [Cited: September 2, 2019.] https://www.alzheimers.org.uk/about-dementia/types-dementia/alzheimers-disease.
[2] Gaugler, Joseph, et al. 2019 Alzheimer’s Disease Facts and Figures. s.l. : Alzheimer’s Association, 2019.
[3] 2014 Update of the Alzheimer’s Disease Neuroimaging Initiative: A review of papers published since its inception. Weiner, Michael W, et al. 6, San Francisco : Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association, 2015, Vol. 11.
[4] Apolipoprotein E and Alzheimer disease: risk, mechanisms, and therapy. Liu, Chia-Chen, et al. 2, Fujian : Nature Reviews Neurology, 2013, Vol. 9.
[5] Apolipoprotein E isoforms and lipoprotein metabolism. Phillips, Michael C. 9, Philadelphia : IUBMB Journals, 2014, Vol. 66.
[6] The Role of Apolipoprotein E in Alzheimer’s Disease. Kim, Jungsu, Basak, Jacob M and Holtzman, David M. 3, St Louis : Neuron, 2009, Vol. 63.
[7] Dacks, Penny. What ApoE Means For Your Health. Cognitive Vitality. [Online] November 16, 2016. [Cited: September 11, 2019.] https://www.alzdiscovery.org/cognitive-vitality/blog/what-apoe-means-for-your-health.
[8] The Complex Role of Apolipoprotein E in Alzheimer’s Disease: an Overview and Update. Mahoney-Sanchez, Laura, et al. 3, Parkville : Journal of Molecular Neuroscience, 2016, Vol. 60.
[9] Understanding the Role of ApoE Fragments in Alzheimer’s Disease. Muñoz, SS, Gerner, B and Ooi, L. 6, Wollongong : Neurochemical Research, 2019, Vol. 44.
[10] ApoE4: an emerging therapeutic target for Alzheimer’s disease. Affieh, Mirna, Korczyn, Amos D and Michaelson, Daniel M. 64, s.l. : BMC Medicine, 2019, Vol. 17.
[11] Apolipoprotein E and Alzheimer disease: pathobiology and targeting strategies. Yamazaki, Yu, et al. 9AB, s.l. : Nature Reviews Neurology, 2019, Vol. 15.
The Importance of Diagnostic Testing in SARS-CoV-2 Adverse Outcomes
SARS-CoV-2 (COVID-19), a highly contagious disease, primarily manifests as an acute respiratory illness, however, for those with health complications, including: autoimmune diseases, asthma, heart disease and diabetes, the risk of developing serious illness and adverse outcomes is much greater. It is estimated that 1 in 6 will experience adverse outcomes that could be life-threatening 1. The spread and devastation of COVID-19 highlights the vital role laboratory diagnostics plays in the diagnosis and management of suspected and affected patients. As the COVID pandemic continues, it is imperative that fast and accurate diagnostic testing strategies are implemented for effective risk stratification and monitoring of treatment and recovery.
In this article, we will review how Randox Reagents can aid in diagnosing and managing SARS-CoV-2 adverse outcomes.
Cytokine Storms
The immune system activates a pro-inflammatory response to enhance host immunity against viruses and decrease colonisation and infection, but only if the pro-inflammatory response is controlled. Uncontrolled pro-inflammatory responses can result in a cytokine storm 2. A cytokine storm is a serious complication associated with SARS-CoV-2, which can trigger life-threatening pneumonia, acute respiratory distress syndrome (ARDS) and multiple organ failure 3, 4. Cytokine storms occur in 5% of severe COVID-19 cases, with several inflammatory cytokines observed at high levels. Due to the elevation of several pro-inflammatory and anti-inflammatory cytokines, a multiplex immunoassay approach can offer several advantages over the widely utilised single ELISA tests. The simultaneous detection of multiple cytokines from a single patient sample will provide clinicians with a comprehensive overview of cytokine markers and complete patient profile, facilitating a personalised treatment plan to be implemented 5, 6.
Inflammation
In COVID-19 patients, CRP testing has proved to perform well in discriminating disease severity and predicting adverse outcomes 7. Elevated CRP levels have been identified in 86% of patients admitted to hospital. CRP measurements are useful in diagnosis, prognosis and monitoring for clinical improvements or deterioration. Moreover, the acute phase reactant, ferritin, has been observed to increase in approximately 60% of COVID-19 patients. In the critically ill COVID-19 patients, extremely elevated ferritin concentrations were recorded, which could be attributed to a cytokine storm and secondary haemophagocytic lymphohistiocytosis (a hyper-inflammatory syndrome associated with multi-organ failure) 8.
Renal Function
Acute kidney injury (AKI) is a common complication in diabetic patients who test positive for COVID-19. Regardless, the National Institute for Health and Care Excellence (NICE) recommend AKI testing in all COVID-19 patients upon hospital admission and their condition monitored throughout their stay 9.
The most commonly utilised screening test for renal impairment is serum creatinine (SCr); however, it is important to consider the accuracy and reliability of the method. Two commercially available methods exist for SCr determination: Jaffe and enzymatic. Whilst the Jaffe method is less expensive, it is more susceptible to interferences which can lead to the misdiagnosis of patients, which isn’t ideal in the current pandemic 7. Moreover, the sensitivity of SCr, regardless of method, in the early detection of renal disease is poor, as SCr is insensitive to small changes in glomerular filtration rate (GFR). Up to 50% of renal function can potentially be lost before significant SCr levels become detectable 8, 9. In comparison, cystatin C (CysC) is a superior marker of renal function and is useful in the determination of the extent of renal damage, as well as distinguishing those with severe and mild COVID-19 10.
Hepatic Function
Abnormal liver function tests significantly increases a COVID-19 patients risk of developing severe disease and complications such as pneumonia 11. Bilirubin levels, 3 times the upper limit have been observed in COVID-19 patients 11, 12. Whilst the diazo method is commonly utilised in bilirubin testing, superior methods exist. The vanadate oxidation (VO) method offers several advantages particularly in haemolytic and lipemic samples. These advantages are particularly evident in neonatal and infant populations where haemolysis is extremely common. Moreover, the VO method offers a wider analytical measurement range for the comfortable detection of clinically important results 13.
Other liver function markers are known to be elevated in COVID-19 patients including both AST and ALT, with markers like albumin decreased.
The Importance of Lp(a) Testing
Lipoprotein(a) / Lp(a), a strong independent marker of cardiovascular disease risk has recently been identified as a key risk marker of cardiovascular complications in COVID-19 patients. Those with either baseline elevated or elevated levels of Lp(a) following COVID-19 infection may be at a significantly increased risk of developing thromboses. Consideration should be given to measurement of Lp(a) and prophylactic anticoagulation of infected patients to reduce the risk. Elevated Lp(a) levels may also cause acute destabilization of pre-existing but quiescent, atherosclerotic plaques, which could induce an acute myocardial infarction (AMI) or cerebrovascular accident (CVA) (stroke) 14.
The size heterogeneity of apo(a) isoforms represents the biggest challenge faced by laboratories in accurately measuring Lp(a). The variable numbers of repeated KIV-2 units in act as multiple epitopes, and so standardisation across calibrators is vital. Unless the calibrants have the same range of isoforms as test samples, those with higher numbers of the KIV-2 repeat, will represent with an overestimation in Lp(a) concentrations and those with smaller numbers of the KIV-2 repeat, will represent with an underestimation. The smaller isoforms are strongly associated with higher Lp(a) concentrations 15.
Lp(a) assays that are standardised to the WHO/IFCC (World Health Organization/International Federation of Clinical Chemistry) reference material, transferring values from mg/dl to nmol/l are more uniform. The assay considered the most reliable commercially available Lp(a) assay is so because: 15
1. The isoform size variations are reduced as a range of calibrators from separate pools of serum used, which covered a range of Lp(a) concentrations.
2. The isoform size and concentrations are inversely correlated, better matching calibrants with test samples.
3. Methods are calibrated in nmol/l and traceable to WHO/IFCC reference material and give acceptable bias compared with the Northwest Lipid Metabolism and Diabetes Research Laboratory (NLMDRKL) gold standard method.
Want to know more?
Contact us or visit our COVID-19 disease management webpage.
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References
[1] Complications coronavirus can cause. https://www.webmd.com/lung/coronavirus-complications#1 (accessed 22 July 2020).
[2] The powerful virus inflammatory response. https://www.mdedge.com/chestphysician/article/189513/infectious-diseases/powerful-virus-inflammatory-response (accessed 4 August 2020).
[3] George A. Cytokine storm: an overreaction of the body’s immune system. https://www.newscientist.com/term/cytokine-storm/ (accessed 22 July 2020).
[5] Del Valle DM, Kim-Schulze S, Huang HH, Beckmann M, Nirenberg S, et al. An inflammatory cytokine signature helps predict COVID-19 severity and death. The Preprint Server for Health Sciences https://www.medrxiv.org/content/10.1101/2020.05.28.20115758v1.full.pdf (accessed 24 July 2020).
The Silent Diabetes Pandemic: A Randox Reagents Blog
The Silent Pandemic
A striking statistic is that an estimated 4.2 million people die annually from Diabetes complications and it is anticipated it will be the seventh leading cause of death by 2030.
Type 2 diabetes mellitus (T2DM) has reached the status of ‘global pandemic’, a phrase we have become all too familiar with due to the current global Covid-19 pandemic, but one we now know not take for granted.
Diabetes is a chronic, potentially life-threatening disease and can cause a myriad of health complications which affect the feet, eyes, kidneys, and cardiovascular health.
Early detection and treatment of diabetes is key, particularly as many people with type 2 diabetes have no signs or symptoms but do have associated risk factors.
Randox is committed to raising awareness of preventative healthcare related to Diabetes through advancing diabetes testing capabilities, including diabetes diagnosis & monitoring, and monitoring of associated complications including; ketoacidosis, renal dysfunction, and metabolic status.
The Randox Diabetes testing panel consists of ten assays including niche and superior performance assays that are compatible with a wide range of clinical chemistry analyzers.
Contact Us
Find out more about the Randox diabetes reagents panel or alternatively you can contact us
reagents@randox.com | www.randox.com/diabetes-reagents
Product availability may vary from country to country. Some products may be for research use only. For more information on product application & availability, please contact your local Randox Representative
Diabetes Reagents Panel
Diagnosis & Monitoring
Fructosamine (Glycated Protein) (Enzymatic Method)
Ketoacidosis
Renal Dysfunction
Creatinine (Enzymatic & JAFFE Methods)
Metabolic Status
World Kidney Day 2021
World Kidney Day 2021
11th March 2021 is World Kidney Day, a worthy global campaign aimed at tackling “the hot topic everyone’s ignoring”.
Raising awareness of a disease that ‘one in every nine’ people worldwide suffer from, is something we take seriously.
Here at Randox, our vision is to improve healthcare worldwide and ensure patients across the globe have access to the latest advancements in clinical diagnostics to tackle diseases such as Chronic Kidney Disease.
This year World Kidney Day 2021 focuses on being able to live well with kidney disease. Many of us take for granted being able to live a normal life without the side effects such as fatigue, pain, depression, sleep problems etc. However Kidney disease can be huge challenge patients and those around them. The impacts of kidney disease can take a toll of day to day life and the ability to participate in activities such as work, travel, and socialising.
Kidney diseases are very common and can be harmful, but the good news is they are also very treatable!
Randox offer a comprehensive panel of kidney health tests, working to ensure timely and accurate diagnosis of kidney function problems to combat patient challenges early.
For example, low levels of albumin indicate signs of kidney damage in the early stages when diagnosis is key. Testing for albumin can identify individuals with diabetic nephropathy (damage to the kidneys caused by diabetes) around 10 years earlier than standard protein tests. The Randox albumin test can therefore enable preventative measures to be taken to reduce your risk of developing kidney disease.
With early diagnosis we can improve patient treatment outcomes and reduce the number of people across the world suffering with kidney health problems.
If you are a clinician or lab interested in running renal function assays, download our Reagents Brochure or email reagents@randox.com
If you want to find out the status of your own Kidney Health, book a health check with Randox Health today.
Want to know more about Randox?
Contact us or visit our homepage to view more.
Why Choose Randox Reagents?
Randox offers an extensive range of third party diagnostic reagents which are internationally recognised as being of the highest quality; producing accurate and precise results. We have the largest test menu of over 100 assays, covering over 100 disease markers including specific proteins, lipids, therapeutic drug monitoring, drugs of abuse, antioxidants, coagulation, diabetes and veterinary testing.
Some of the key benefits of Randox Reagents include:
Reduced costs
Randox reagents can help create cost-savings for laboratories through excellent reagent stability; by eliminating the need for costly re-runs through the excellent quality of products. We also offer a range of kit sizes including smaller kit sizes for niche tests to reduce waste.
Reduce the risk of errors and have confidence in patient results
Our traceability of material and extremely tight manufacturing tolerances ensure uniformity across reagent batches reducing lot-to-lot variability. In addition, our assays are validated against gold-standard methods, giving you the confidence that you are sending out the correct patient results.
Reduced labour
Reduce your time spent on running tests through liquid ready-to-use reagents, automated methods (compared to the traditional laborious ELISA methods used for some tests such as cystatin C or adiponectin) as well as our easy-fit options.
Expand your routine testing
With speciality assays for 195 of the most common clinical chemistry analysers; assays which usually require dedicated equipment, or was previously only available as an ELISA, can now be run on automated biochemistry analysers, allowing your laboratory to expand its routine test menu. For example, cystatin C, adiponectin, TxBCardio™ and many more.
Bring testing in-house
With smaller kit sizes and excellent reagent stability (most are stable for 28 days on-board the analyser), you don’t have to worry about reagent wastage, allowing testing to be brought in-house rather than sent to external laboratories.
Expand your test menu without expanding your lab
There is no need to buy any extra equipment in order to expand your test menu. Our reagents can be programmed onto the majority of the most common biochemistry analysers. At present, we have hundreds of applications available.
Visit our Reagents Resource Hub and Download our reagents brochure for information on the full range of biochemistry reagents.
Randox reagents are available for a wide range of clinical chemistry analysers. For more information, please contact reagents@randox.com
Diabetes diagnosis with Randox Reagents
The prevalence of diabetes is steadily increasing across the world, with approximately 422million people worldwide with diabetes and is currently one of the leading causes of death in the world. A diabetes diagnosis comes in three forms; Type 1 Diabetes Mellitus, Type 2 Diabetes Mellitus and Gestational Diabetes. Each type of diabetes can have long-term, detrimental effects to your health if it is not controlled, with some of the key complications being heart disease, kidney damage, retinopathy and even limb amputations.
Diabetes can be controlled through maintaining a healthy diet and regular exercise, however in situations where complications occur, innovative testing can aid in the prevention and management of detrimental consequences to patients. Randox Reagents offer a range of high performance and unique tests which can be used to manage complications of diabetes such as:
Diabetic Nephropathy
Kidney disease is a life threatening complication of diabetes, commonly called diabetic nephropathy in patients with diabetes. Around 40% of people with diabetes develop diabetic nephropathy, characterised through prolonged periods of high glucose levels in the blood. To effectively monitor diabetic nephropathy, it is essential to test cystatin C levels in patients, which is a useful indicator of renal function in patients where creatinine measurements are unreliable. Unlike creatinine, cystatin C does not have a ‘blind area’ – up to 50% of renal function can be lost before significant creatinine elevation occurs. This makes cystatin C capable of detecting early stage kidney dysfunction in patients with diabetic nephropathy.
Microalbumin testing is also important to identify patients with diabetic nephropathy approximately 5-10 years earlier than proteinuria tests, helping to reduce the incidence of end stage renal disease. This is because low albumin concentrations in the urine are the earliest market of renal damage and therefore enable preventative measures to be taken.
Metabolic Syndrome
Metabolic syndrome is a severe complications of uncontrolled diabetes which contains a number of conditions which occur together, increasing your risk of heart disease, stroke and diabetes. Metabolic syndrome can be monitored through measuring Non-Esterified Fatty Acids (NEFA), which are molecules released from triglycerides by the action of the enzyme lipase and are transported in the blood bound to albumin. NEFA contributes a small proportion of the body’s fat, however they provide a large part of its energy, with elevated concentrations having adverse effects on both carbohydrate and lipid metabolism.
With the global burden of diabetes rising year on year, diabetes complications monitoring has never been more important. Randox Reagents offer a wide range of innovative testing to laboratories, to help clinicians accurately diagnose and monitor diabetes complications.
Download our diabetes brochures to find out about our full range of diabetes reagents
Randox reagents are available for a wide range of clinical chemistry analysers. For more information, please contact reagents@randox.com
H-FABP for Acute Kidney Injury Testing Revealed by Randox
A new testing application for the biomarker Heart-Type Fatty Acid-Binding Protein (H-FABP) has been announced by global diagnostics company Randox Laboratories.
Whilst H-FABP is most commonly recognized as an early biomarker of myocardial infarction, the assay’s clinical utility in cardiac surgery associated acute kidney injury (CSA-AKI) is notable. Studies have shown that patients who developed AKI following cardiac surgery had elevated levels of H-FABP both pre-and postoperatively compared to the patients who did not.
Susan Hammond, Randox Product Specialist, explained the new application for H-FABP;
“Cardiac surgery-associated acute kidney injury (CSA-AKI) is a well-recognized postoperative complication of cardiac surgery and is the second most common cause of AKI in the intensive care unit (ICU) – occurring in up to 30% of patients.
“Several AKI studies exist focusing on the measurement of H-FABP levels before, during and after cardiac surgery, one of which found that the post-operative H-FABP levels in patients who experienced any AKI increased 8-fold. It was also noted that the levels of those with severe AKI increased 13-fold and that 10.8% of patients who died from subsequent AKI all had elevated pre-operative levels of H-FABP.
“The Randox H-FABP assay is therefore an independent marker of AKI following cardiac surgery, and can furthermore be used as a CSA-AKI risk assessment assay even in advance of the procedure.”
It has been identified that certain patient groups are more susceptible to CSA-AKI and vulnerability can depend on age, sex, pre-existing cardiac dysfunction, pre-existing chronic kidney disease (CKD), previous cardiac surgery or comorbidity.
Susan Hammond added;
“The ability to include biomarkers that aid in the risk assessment and treatment plan management of a patient is significant. Utilizing H-FABP alongside traditional biomarkers to assess CSI-AKI risk allows the clinician to gain stronger clinical insight in how to improve patient outcomes.”
Key Benefits of the Randox H-FABP assay
A niche product from Randox meaning that Randox are one of the only manufacturers to offer the H-FABP assay in an automated biochemistry format
CE marked for diagnostic use
Automated assay offering a more convenient and time efficient method for H-FABP measurements compared to traditional testing
Exceptional correlation of r=0.97 when compared against other commercially available methods
Applications available detailing instrument-specific settings for the convenient use of the Randox H-FABP assay on a wide range of clinical chemistry analysers
Liquid ready-to-use format for convenience and ease-of-use
Latex enhanced immunoturbidimetric method delivering high performance compared to traditional ELISA testing
Rapid results within fourteen minutes, depending on the analyser.
Wide measuring range of 0.747 – 120ng/ml for the early detection of clinically important results
Dedicated H-FABP controls and calibrator available offering a complete testing package
Total Bile Acids: The Value of Fifth Generation Tests
Bile acids are water-soluble, amphipathic end products of cholesterol metabolism and are involved in liver, biliary and intestinal diseases. They are formed in the liver and are absorbed in the small intestine before being excreted. The fundamental role of bile acids is to aid in the digestion and absorption of fats and fat-soluble vitamins in the small intestine.1
Intrahepatic Cholestasis of Pregnancy
Intrahepatic cholestasis of pregnancy (ICP) is a pregnancy-specific liver disorder. It can be indicated by pruritus, jaundice, elevated total bile acids and/or serum transaminases and usually affects women during the second and third trimester of pregnancy.2,3
Intrahepatic Cholestasis of pregnancy or Obstetric Cholestasis is a condition that restricts the flow of bile through the gallbladder resulting in a build-up of bile acids in the liver.3 Due to the build-up, bile acids leak into the bloodstream where they are detected at concerning levels. It is an extremely serious complication of pregnancy that can lead to the increased risk of premature birth or even stillbirth, as such it is vital that women with the disease are monitored carefully.
In healthy pregnancies, there is very little increase in total bile acid levels although a slight increase is likely to be seen in the third trimester. Measurement of total bile acids in serum is thought to be the most suitable method of diagnosing and monitoring ICP.6
According to several reports total bile acid levels in ICP can reach as high as 100 times the upper limit of a normal pregnancy. It has been reported that a doubling in maternal serum bile acids, results in a 200% increased risk of stillbirth with total bile acids thought to trigger the onset of preterm labour. Additionally, bile acids can affect the foetal cardiovascular system as it has been found that there are often cardiac rhythm disturbances in the foetus due to the elevated bile acids in circulation.5
Although it is a rare condition, with only 0.3-0.5% of women likely to develop ICP, it can have extreme risks and so it is important to properly diagnose and monitor the condition.6 ICP increases the risk of meconium staining of the amniotic fluid and is reported to be a sign of foetal distress. This complication is found in 16-58% of all ICP cases, worryingly 100% of cases have resulted in foetal death. The frequency of this condition is found to be greater in pregnancies with higher levels of serum total bile acids.
Risk factors
There are several risk factors associated with ICP such as a family history of ICP, use of oral contraceptives, assisted reproduction techniques and multiple gestation. Genetic influence accounts for approximately 15% of ICP cases. Dietary selenium is a contributing environmental factor as serum selenium levels often decrease throughout pregnancy. Further to this, incidences of ICP rise in the winter months, most likely due to the fact selenium levels are naturally less during these months.7,8
Total Bile Acids
In addition to ICP, bile acid levels are also measured in the diagnosis of other liver disorders. The bile acids test in an extremely sensitive indicator of liver function, capable of detecting changes in hepatic function before clinical symptoms arise, thus providing valuable information that standard liver function tests cannot. As a result of its high sensitivity, bile acids can be used to assess liver function in transplant patients, allowing monitoring of the transplant success and of antirejection therapy. The bile acids test is most beneficial when used in conjunction with standard liver function tests such as ALT and AST which are markers of liver damage rather than liver function.
Measurement of Total Bile Acids
The enzyme cycling method, also known as the Fifth Generation Bile Acids test, is a method that allows for signal amplification through cycled regeneration reactions as can be seen in Figure 1. In the presence of Thio-NAD, the enzyme 3-α hydroxysteroid dehydrogenase (3-α HSD) converts bile acids to 3-keto steroids and Thio-NADH. The reaction is reversible and 3-α HSD can convert 3-keto steroids and Thio-NADH to bile acids and Thio-NAD. In the presence of excess NADH, the enzyme cycling occurs efficiently and the rate of formation of Thio-NADH is determined by measuring specific change of absorbance at 405 nm and is proportional to the amount of total bile acids in the sample. The analysing capability of the fifth generation total bile acids assay is far beyond the performance of conventional bile acid tests.10,11
Figure 1: The assay principle⁹
Inadequacies of Traditional Bile Acids Assays
Determining the cause and extent of liver damage is important in guiding treatment decisions and preventing disease progression. Standard liver function tests include; ALT, AST, ALP, GGT and Bilirubin. The measurement of TBA is most beneficial in conjunction with these standard liver tests and offers unrivalled sensitivity allowing identification of early stage liver dysfunction. There are several commercial methods available for the detection and measurement of TBA in serum. Traditional TBA tests based on the enzymatic method use nitrotetrazolium blue (NBT) to form a formazan dye. The reaction is measured at 546nm and the intensity of the colour is proportional to the concentration of bile acids.
Newer methods such as the enzyme cycling method or fifth generation methods offer many advantages including greater sensitivity, liquid reagents, small sample volumes and reduced instrument contamination from formazan dye. Additionally, the fifth generation assay does not suffer from interference from lipaemic or haemolytic samples. Both lipemia and haemolysis are common in new-borns and pregnant women, so this further supports that the fifth generation test is more sensitive for these sample types.12
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References
[1] The continuing importance of bile acids in liver and intestinal disease. A.f., Hofmann. 1999, Arch Intern Med, pp. 2647-2658.
[2] Diagnostic and Therapeutic Profiles of Serum Bile Acids in Women with Intrahepatic Cholestasis of Pregnancy – A Pseudo-Targeted Metabolomics Study. Cui, Yue. Xu, Biao. Zhang, Xiaoqing. He, Yifan. Shao, Yong. Ding, Min. s.l. : Clinica Chimica, 2018, Vol. 483.
[3] Randox Laboratories. Bile Acids Test for Obstetric Cholestasis – A serious complication of pregnancy. 2012.
[4] British Liver Trust (2019) Facts about Liver Disease, Available at: https://www.britishlivertrust.org.uk/about-us/media-centre/facts-about-liver-disease/ (Accessed: 18th June 2019).
[5] .Geenes, Victoria. Williamson, Catherine. 17, s.l. : World J Gastroenterol, 2009, Vol. 15.
[6] Howland, Genevieve. Cholestasis of Pregnancy: Why You Can’t Ditch the Itch. Mama Natural. [Online] December 22, 2018. [Cited: February 19, 2019.] https://www.mamanatural.com/cholestasis-of-pregnancy/.
[7] Bile Acid Levels and Risk of Adverse Perinatal Outcomes in Intrahepatic Cholestasis of Pregnancy: A Meta-Analysis. Cui, Donghua, et al.
[8] Intrahepatic Cholestasis of Pregnancy. Chivers, Sian. Williamson, Catherine. 7, 2018, Vol. 28.
[9] Masoud, N; Neill, S.H. Serum bile acids as a sensitive biological marker for evaluating hepatic effects of organic solvents. Available from URL: https://www.ncbi.nlm.nih.gov/pubmed/23885947 [Accessed 1 November 2018]
[10] Microassay of Serum Bile Acids by an Enzymatic Cycling Method. Komiyama, Y, et al. 10, s.l. : Chemical and Pharmaceutical Bulletin, 1982, Vol. 30.
[11] Evaluation of a Colorimetric Enzymatic Procedure for Determining the Total Bile Acids in the Blood. Agape, V, et al. 3, s.l. : Minerva Gastroenterologica e Dietologica, 1989, Vol. 35.
[12] Total Bile Acids Test & Clinical Diagnosis. Diazyme. 2019.
Diabetes: The Role of Fructosamine
Diabetes Week is an annual week to raise awareness of diabetes. This year, the aim is to increase the public’s understanding of diabetes 1. Diabetes mellitus (DM) is a global epidemic, increasing at an alarming rate and burdening healthcare systems 2. DM is a life-long condition characterised by the body’s inability to produce / respond to insulin resulting in the abnormal metabolism of carbohydrates and elevated blood glucose levels.
Whilst it is important to increase the public’s understanding of DM, it is imperative that clinicians and physicians are aware of the different in vitro diagnostic tests to diagnose and monitor DM. Not only is this vital, but is also important that clinicians and physicians also understand the different methodologies available when choosing the diagnostic test.
It has been highlighted in numerous clinical studies that diabetic complications may be reduced through the long-term monitoring and tight control of blood glucose levels. Both fasting plasma glucose (FPG) and glycated haemoglobin A1c (HbA1c) tests are universally accepted as reliable measurements of diabetic control. However, studies have emerged highlighting the role of fructosamine in diabetes monitoring. Whilst HbA1c provides an index of glycaemia over 2 to 3 months, fructosamine provides this index over the course of 2 to 3 weeks, enabling closer monitoring of diabetic control 1.
Drawbacks of Traditional Diabetes Tests
The FPG test measures the level of blood sugars which is used to diagnose and monitor diabetes based on insulin function. The main drawback of this test is that a hormone called glucagon, produced in the pancreas, is triggered during prolonged fasting, signalling the liver to release glucose into the bloodstream. In diabetic conditions, either the body is unable to generate enough insulin or cannot appropriately respond to insulin. Consequently, FPG levels remain high 4.
In the 1980’s, HbA1c was incorporated into clinical practice as HbA1c levels correlated well with glycaemic control over a 2 to 3-month period. The main drawback of this test is that any condition that reduces the survival rate of erythrocytes such as haemolytic anaemia will falsely lower the HbA1c test results, regardless of the assay method utilised 5.
Fructosamine Testing
In a diabetic patient where blood glucose levels are abnormally elevated, the concentration levels of fructosamine also increase as fructosamine is formed by a non-enzymatic Maillard reaction between glucose and amino acid residues of proteins. During this glycation process, an intermediate labile Schiff base is produced which is converted to a more stable ketoamine (fructosamine) via an Amadori rearrangement 2.
Fructosamine has been identified as an early indicator of diabetic control compared to other markers such as HbA1c. Red blood cells live for approximately 120 days, HbA1c represents the average blood glucose levels for the previous 2 to 3 months. Conversely fructosamine has a shorter lifespan, about 14 to 21 days, reflecting average blood glucose levels from the previous 2 to 3 weeks. Due to the shorter time span of fructosamine, it is also used to evaluate the effectiveness of medication changes and to monitor the treatment of gestational diabetes. The test is also particularly useful in situations where HbA1c cannot be reliably measured e.g. haemolytic anaemia, thalassemia or with genetic haemoglobin variants 5.
Fructosamine Assay Methodology
The most commonly utilised method for fructosamine testing is the colorimetric method. Whilst widely available, automated and inexpensive, the main drawback is the lack of standardisation across the different fructosamine assays 4.
Randox, on the other hand, utilise an enzymatic method, offering improved specificity and reliability compared to conventional NBT-based methods. The Randox enzymatic method does not suffer from non-specific interferences unlike existing methods which can also be time consuming and difficult to automate.
The Randox fructosamine assay is also standardised to the highest level as the Randox fructosamine calibrator and control is assigned relative to human serum glycated with 14C-glucose, which directly reflects the nature of the patient sample.
With an excellent stability of 28 days on-board the analyser, the Randox fructosamine assay is developed in a liquid ready-to-use format for convenience and ease-of-use.
Randox offer fully automated applications detailing instrument-specific settings for the convenient use of the Randox fructosamine assay on a wide range of clinical chemistry analysers.
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References
[1] Diabetes UK. Diabetes Week. [Online] 2019. [Cited: May 31, 2019.] https://www.diabetes.org.uk/get_involved/diabetes-week.
[2] Gounden, Verena and Jialal, Ishwarlal. Fructosamine. [Online] January 23, 2019. [Cited: April 11, 2019.] https://www.ncbi.nlm.nih.gov/books/NBK470185/.
[3] World Health Organization (WHO). Diabetes. [Online] October 30, 2018. [Cited: May 2, 2019.] https://www.who.int/news-room/fact-sheets/detail/diabetes.
[4] Manzella, Debra. The Fasting Plasma Glucose Test. very well health. [Online] November 16, 2018. [Cited: April 11, 2019.] https://www.verywellhealth.com/understanding-the-fasting-plasma-glucose-test-1087680.
[5] BMJ. Using haemoglobin A1c to diagnose type 2 diabetes or to identify people at high risk of diabetes. [Online] 2014. [Cited: April 11, 2019.] https://www.bmj.com/content/348/bmj.g2867/rr/695927.
