Patient result monitoring of HbA1c shows small seasonal variations and steady decrease over more than 10 years.

OBJECTIVES: Internal and external quality assurance materials often use highly processed matrixes. This can render the materials non-commutable. Monitoring laboratory methods with patient medians helps in identifying and correcting systematic errors that may affect diagnostic accuracy. The aim of the present study was to use HbA1c patient results for monitoring of method performance over time. METHODS: Test HbA1c results from 2010 to 2022 was analyzed (n=722,553) regarding changes over time and seasonal variation. The HbA1c testing was initially performed on a Cobas 501 instrument using immunological detection but in May 2017 the method was replaced by capillary electrophoresis on Capillarys 3 Tera. RESULTS: There was a steady decrease in HbA1c values. From 2011 to 2021 the decrease was for 0.10 percentile 6.6 %, lower quartile 7.9 %, median 10.2 %, mean values 9 %, upper quartile 11.2 %, and 0.90 percentile 9.3 %. No clear shift in HbA1c levels was observed due to the shift in methods. The median HbA1c values per month was approximately 44 mmol/mol (6.2 %, DCCT/NGSP). The only month with a median HbA1c that differed by more than 1 mmol/mol was July with a median value of 42 mmol/mol (6.0 %). CONCLUSIONS: The patient data showed a similar decrease as in the National Diabetes Register which indicates that the method is stable over time without any sudden changes and that the seasonal variation is low. The continuous decrease in HbA1c values over time is most likely to a shift towards earlier detection of patient with diabetes and improved treatment.

Analysis of HbA1c using microfluidic card (Capitainer qDBS card) as a pre-step before determination of the HbA1c value with an immunological method.

The objective of the study was to evaluate Capitainer's quantitative dried blood spots (qDBS) card for Hemoglobin A1c (HbA1c) testing. qDBS cards can be used for at-home sampling for HbA1c determination in a Swedish laboratory setting. A total of 153 routine requested HbA1c samples were used in this evaluation of microfluidic cards (qDBS). The HbA1c was extracted from the disc and HbA1c was determined at cobas 6000 instruments with immunological technology. The results were compared with results from traditional venous HbA1c testing. The reproducibility of using this elution procedure was 4.0% measured as coefficient of variation at a HbA1c concentration of 51 mmol/mol. Analytical performance specifications for HbA1c < 52 mmol/mol using DBS card (c501) compared with assigned values from Capillarys 3 was (y) = 1.03 x Capillarys 3(x) - 0.87; R2 = 0.97. There is a good agreement between HbA1c determined by traditional HbA1c testing and determination from Capitainer's qDBS cards. This shows that the technology could be used for out-of doctor's office testing.

Reference Intervals for Plasma Free Kappa and Lambda Chains and Kappa/Lambda Ratio using PENIA.

BACKGROUND: Determination of free light chains is used increasingly for patients with multiple myeloma and other plasma cell dyscrasias. The aim of the present study was to define reference intervals for free kappa and lambda chains and kappa/lambda ratio in lithium heparin plasma and compare the test results with cystatin C based estimated glomerular filtration rate. METHODS: Free kappa and lambda chains were measured in Liheparin plasma from 222 healthy blood donors using free light chain reagents and a BNII nephelometer from Siemens Diagnostics. RESULTS: Calculated reference intervals for kappa chain, free was 4.73 mg/L (90% confidence interval 4.00 - 5.45) - 22.66 mg/L (20.33 - 24.98), for lambda chain, free was 4.33 mg/L (3.70 - 4.95) - 29.28 mg/L (26.96 - 31.59), and for Kappa/Lambda Chain ratio 0.59 (0.56 - 0.62) - 1.46 (1.37 - 1.56). There was no need for gender or age specific reference intervals. Cystatin C based estimated glomerular filtration rate had a significant effect on the levels of free light chains. CONCLUSIONS: The study presents reference intervals for plasma free light chains and compared results of estimated glomerular filtration rate with free light chains of kappa and lambda.

Accuracy of determination of free light chains (Kappa and Lambda) in plasma and serum by Swedish laboratories as monitored by external quality assessment.

BACKGROUND: Free light chain (FLC) measurements are important in diagnosing monoclonal gammopathies. As FLC are heterogeneous, different reagents and instruments for measuring FLC concentrations may give diverging results that affect assessment of patients with monoclonal gammopathies. Here we investigated agreement between different FLC methods using data from the Swedish external quality assurance (EQA) programme. METHODS: The two main FLC assays, N Latex FLC (Siemens) and Serum Freelite (The Binding Site), using four nephelometric or turbidimetric instrument platforms, were compared. Results from 27 EQA rounds distributed to 11-16 Swedish hospital laboratories during 2015-2020 were investigated. RESULTS: The kappa (κ) FLC measurements deviated significantly over time, but when only nephelometry was used, deviation from the mean was lower (median ranges: -5% to 13 %). The CV was significantly higher for the Freelite assay (mean CV = 8.7) than for the N latex assay (mean CV = 5.7) (p < 0.0001). The coefficient of determination between all combinations of reagents and instrument platforms used was generally good (r2 = 0.76-0.87), and the correlation slope acceptable (0.81-1.2). For lambda (λ) FLC measurements, no concordance between combinations of instruments and reagents is apparent, deviating between -40 % to + 48 % from the mean. The CV was significantly higher for the combination with nephelometry and the Freelite assay (CV mean = 13.9 %) than nephelometry and the N latex assay (CV mean = 9.9 %) (p <0.001). The coefficient of determination varied between combinations of reagents and instrument platforms (r2 = 0.59-0.89) and the slope ranged between 0.48 and 1.5. Significant differences between the two reagents used were sometimes noted. CONCLUSIONS: Imprecision in λFLC affects the κFLC/λFLC ratio. This may be important in clinical assessment of patients, especially differentiating between monoclonal and polyclonal gammopathies.

Metabolomics of Cerebrospinal Fluid from Healthy Subjects Reveal Metabolites Associated with Ageing.

To increase our understanding of age-related diseases affecting the central nervous system (CNS) it is important to understand the molecular processes of biological ageing. Metabolomics of cerebrospinal fluid (CSF) is a promising methodology to increase our understanding of naturally occurring processes of ageing of the brain and CNS that could be reflected in CSF. In the present study the CSF metabolomes of healthy subjects aged 30-74 years (n = 23) were studied using liquid chromatography high-resolution mass spectrometry (LC-HRMS), and investigated in relation to age. Ten metabolites were identified with high confidence as significantly associated with ageing, eight with increasing levels with ageing: isoleucine, acetylcarnitine, pipecolate, methionine, glutarylcarnitine, 5-hydroxytryptophan, ketoleucine, and hippurate; and two decreasing with ageing: methylthioadenosine and 3-methyladenine. To our knowledge, this is the first time the CSF metabolomes of healthy subjects are assessed in relation to ageing. The present study contributes to the field of ageing metabolomics by presenting a number of metabolites present in CSF with potential relevance for ageing and the results motivate further studies.

Accuracy of determination of the glomerular filtration marker iohexol by European laboratories as monitored by external quality assessment.

Background Glomerular filtration is the most important kidney function. The most accurate glomerular filtration rate (GFR) estimates are based on the clearance of exogenous filtration markers. Of these, iohexol is the only exogenous marker that is included in an external quality assessment (EQA) scheme. The aim of the present study was to evaluate the performance of the European laboratories participating in Equalis' EQA scheme for iohexol. Methods Weighed amounts of iohexol (Omnipaque) were added to plasma samples and distributed to laboratories participating in the EQA scheme for iohexol. All laboratories performed the assays in a blinded fashion. Results The number of participating laboratories varied between 27 and 34 during the study period. Iohexol was determined by HPLC in 77% of the laboratories and by UPLC/MS/MS methods in 15% of the laboratories. The mean interlaboratory coefficient of variation was 4.7% for the HPLC methods and 6.4% for the UPLC/MS/MS methods. The mean bias between calculated and measured iohexol values was -1.3 mg/L (95% confidence interval ±0.3) during the first part of the study period and 0.1 mg/L (±0.3) during the later part. Conclusions The low interlaboratory variation demonstrates that iohexol can be measured reliably by many laboratories and supports the use of iohexol as a GFR marker when there is a need for high quality GFR measurements.

Analysis of HbA1c on an automated multicapillary zone electrophoresis system.

Hemoglobin A1c (HbA1c) is a frequently requested laboratory test and there is thus a need for high throughput instruments for this assay. We evaluated a new automated multicapillary zone electrophoresis instrument (Capillarys 3 Tera, Sebia, Lisses, France) for analysis of HbA1c in venous samples. Routine requested HbA1c samples were analyzed immunologically on a Roche c6000 instrument (n = 142) and then with the Capillarys 3 Tera instrument. The Capillarys 3 Tera instrument performed approximately 70 HbA1c tests/hour. There was a strong linear correlation between Capillarys 3 Tera and Roche Tina-Quant HbA1c Gen 3 assay (y = 1.003x - 0.3246 R2 = .996). The total CV for the 12 capillaries varied between 0.8 and 2.2% and there was a good agreement between duplicate samples (R2 = .997). In conclusion, the Capillarys 3 Tera instrument has a high assay capacity for HbA1c. It has a good precision and agreement with the Roche Tina-Quant HbA1c method and is well suited for high volume testing of HbA1c.

Detection of recombinant human EPO administered to horses using MAIIA lateral flow isoform test.

Doping of horses with recombinant human erythropoietin (rHuEPO) to illegally enhance their endurance capacity in horseracing has been reported during the last years. This leads to increased blood viscosity which can result in sudden death and is of concern for the horse welfare. Additionally, the horse can start production of rHuEPO antibodies, which cross-reacts with endogenous equine EPO and can lead to severe anaemia and even death. In this study, a novel micro-chromatographic method, EPO WGA MAIIA, has been tested for the capability in plasma and urine samples to detect administration of erythropoiesis-stimulating agents, like the rHuEPO glycoprotein varieties Eprex and Aranesp, to horses. After administration of 40 IU Eprex kg(-1) day(-1) to seven horses during 6 days, the presence of Eprex in horse plasma was detected up to 2-5 days after last injection. In urine samples collected from two horses, Eprex was detected up to 3 days. A single injection of Aranesp (0.39 µg/kg) was detected up to 9 days in plasma and up to 8 days, the last day of testing, in the urine sample. The LC-FAIMS-MS/MS system, with 1 day reporting time, confirmed the presence of Eprex up to 1 day after last injection for six out of seven horses and the presence of Aranesp up to 5 days after last injection in plasma samples. The MAIIA system showed to be a promising tool with high sensitivity and extremely short reporting time (1 h).