BACKGROUND: To accurately assess hypogammaglobulinemia at birth, it is essential to determine the reference intervals of serum immunoglobulin (IgG) levels in newborns. In the present study, we determined the gestational...BACKGROUND: To accurately assess hypogammaglobulinemia at birth, it is essential to determine the reference intervals of serum immunoglobulin (IgG) levels in newborns. In the present study, we determined the gestational age (GA)-/birth weight (BW)-dependent percentile-based reference intervals of serum IgG levels and converted them into simple formulas for practical use. METHODS: Serum IgG levels were measured in cord blood from 2902 newborns delivered at 22 to 41 weeks of GA or 264 to 4642 g of BW after exclusion of those with congenital disorders. Linear regression analysis was used to correlate GA and UC-IgG levels and BW and UC-IgG levels. After calculation of the percentile values of UC-IgG levels for each GA or BW, the distributions were approximated by the least-squares method. Fitness was evaluated by the coefficient of determination (). RESULTS: Significant positive correlations were found both between GA and UC-IgG levels ( = 0.790, < 0.001) and BW and UC-IgG levels ( = 0.626, < 0.001). The distribution of the 5%ile of UC-IgG levels (Y) by GA or BW (X) was approximated as a straight line (Y = 37.5 *X - 775.8; Y = 0.161 *X + 95.34, respectively). The fitness was stronger in the GA-derived formula than the BW-derived formula ( = 0.973 vs 0.913). CONCLUSIONS: We established GA-/BW-dependent reference percentile-based intervals for serum IgG levels using cord blood from 2902 newborns without congenital disorders. Using GA-dependent reference intervals may be useful for assessing hypogammaglobulinemia at birth.
BACKGROUND: CA19-9 is elevated in pancreatic cancer and other malignancies, and commonly used in clinical practice. Unfortunately, CA19-9 immunoassays are not harmonized, and reference intervals may differ between assays...BACKGROUND: CA19-9 is elevated in pancreatic cancer and other malignancies, and commonly used in clinical practice. Unfortunately, CA19-9 immunoassays are not harmonized, and reference intervals may differ between assays. The aim of this study was to establish the reference interval of the ADVIA Centaur/Atellica IM CA19-9 assay in an apparently healthy Singapore adult population. METHODS: This is a retrospective cross-sectional study. De-identified data from Health Screening participants were extracted from our database. Subjects with biochemical results suggesting anaemia, diabetes mellitus, viral hepatitis or abnormal liver, and renal and tumour markers were excluded. Outlier and subclass analyses by age and sex were performed. CA19-9 reference limits and 90% confidence intervals were then determined for candidate subclasses. RESULTS: Data from 12,174 subjects (5846 males and 6328 females) were available after exclusion criteria were applied. CA19-9 results did not follow a normal distribution and were higher in females compared to males ( < .001). Although CA19-9 means were statistically different between certain age groups, the evaluable 99th percentile reference limits were not statistically different. The overall 99th percentile reference limits for the Centaur/Atellica CA19-9 assay was 37 U/mL for males 21-80 years, and 60 U/mL for females 21-80 years. CONCLUSIONS: Our results suggest that separate CA19-9 reference intervals should be applied for males and females.
BACKGROUND AND OBJECTIVE: The disaccharide loading test is a method to assess gastric mucosal damage. Since Trelan-G75, which is used for the sugar tolerance test, contains disaccharide maltose, if maltose is detected at...BACKGROUND AND OBJECTIVE: The disaccharide loading test is a method to assess gastric mucosal damage. Since Trelan-G75, which is used for the sugar tolerance test, contains disaccharide maltose, if maltose is detected at a high sensitivity in the sample blood used in the sugar tolerance test, screening for upper gastrointestinal mucosal damage can be made simultaneously with the sugar tolerance test for the diagnosis of diabetes. METHODS: Glucose-6-phosphate is generated by treating maltose with maltose phosphorylase, β-phosphoglucomutase, and glucose-1,6-bisphosphate. Then, change in the absorbance at 405 nm is measured by the enzymatic cycling method using Thio-NADP, β-NADPH, and Glucose-6-phosphate dehydrogenase. After evaluating the optimal condition for this method, it is mounted on an automatic biochemical analyzer, and samples after the sugar tolerance test were assayed. RESULTS: Regarding the performance of this method, the repeatability was 10-50 μmol/L with a CV of ≤1.1%. Concerning the assay range, a curve passing the origin with a range of linearity up to 120 μmol/L was obtained. No effect of dyes or sugars in the blood was noted. As a result of application to patients with gastric mucosal disorders (those who had a health checkup), significant differences were observed depending on the stage of atrophic gastritis. DISCUSSION: This method has a high sensitivity and a high precision and can be used for high-speed analysis on an automatic analyzer. It has the potential to be used as a screening test for gastric mucosal damage.
BACKGROUND: Ketamine is an NMDAR antagonist with aggregating use across many areas of medicine. P450 enzymes heavily metabolise ketamine, where norketamine is a first pass formed metabolite following initial N-demethylat...BACKGROUND: Ketamine is an NMDAR antagonist with aggregating use across many areas of medicine. P450 enzymes heavily metabolise ketamine, where norketamine is a first pass formed metabolite following initial N-demethylation. Serum ketamine monitoring is becoming increasingly important, requiring a sensitive method with a robust lower limit of quantitation. METHODS: Samples were prepared using protein precipitation or solid phase extraction. Ion suppression was investigated to optimise sample preparation technique, followed by reverse-phase chromatography coupled with tandem mass spectrometry to analyse extractions using a Waters Xevo TQ-S Micro and associated Acquity chromatography systems. Performance characteristics were analysed to validate the assay. RESULTS: Ketamine and norketamine retention times were 1.28 and 1.23 min, respectively. Ketamine and norketamine precursor ions fragmented into 2 distinguishable product ions (238.14 > 207.18/125.06 and 224.1 > 178.96/124.86). Performance characteristics include an assay recovery of 103.7% (ketamine) and 96.3% (norketamine), lower limit of quantitation 36.2 µg/L (ketamine) and 38.9 µg/L (norketamine), and intra-assay imprecision ≤ 7.04% on average. CONCLUSIONS: A robust and reproducible assay with limited sample preparation has been designed and validated. The linearity of the assay covers all ranges of interest reported in the literature. Ion suppression was clearly reduced via use of solid phase extraction. The method will form the basis of ketamine monitoring and providing valuable patient information on tolerance and metabolism.
BACKGROUND: Isoelectric focusing (IEF) is a method with an exquisite resolution, and coupled with affinity immunoblotting (AIB), it can provide superior sensitivity to detect monoclonal free light chains (FLC). METHODS:...BACKGROUND: Isoelectric focusing (IEF) is a method with an exquisite resolution, and coupled with affinity immunoblotting (AIB), it can provide superior sensitivity to detect monoclonal free light chains (FLC). METHODS: We tested the hypothesis that IEF/AIB is more sensitive and specific for monoclonal FLC detection in serum and urine samples than conventional methods, that is, electrophoresis (ELP), immunofixation (IF) and serum FLC ratio assessment. Investigation included 107 samples of 68 patients, among which 21 multiple myeloma patients were recently tested for minimal residual disease and 18 patients with AL amyloidosis. RESULTS: Monoclonal FLC were detected by IEF/AIB in 37% of serum samples negative for monoclonal FLC on ELP/IF. As for urine samples, significant advantage of the IEF/AIB over ELP/IF was not demonstrated. Considering both serum and urine results, IEF/AIB definitely revealed monoclonal FLC in 20/83 (24%) of ELP/IF-negative samples. FLC ratio was abnormally high (>1.65) in all 11 patients definitely positive for monoclonal FLC kappa by IEF/AIB but also in 16/47 (34%) IEF/AIB-negative samples. Abnormally low values (<0.26) were found only in 10/28 samples (36%) positive for monoclonal FLC lambda. Appropriate use of renal FLC ratio reference range reduced the number of presumably false positives (6/47, i.e. 13%) but not false negatives (17/28, i.e. 61%). CONCLUSIONS: The IEF/AIB method is more sensitive than IF and might be used in patients with negative IF results before deciding whether to proceed to minimal residual disease testing.
Özcan Ö, van Wijk JA, Bosch AM
… +3 more, den Elzen WP, Heijboer AC, Fischer JC
Ann Clin Biochem
· 2024 Mar · PMID 38008911
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This case report describes the positive interference of the commonly used skin protective barrier cream used together with urine collection bags on the benzethonium chloride method for urine protein measurements in a 6-m...This case report describes the positive interference of the commonly used skin protective barrier cream used together with urine collection bags on the benzethonium chloride method for urine protein measurements in a 6-month-old female baby, leading to falsely elevated results. The interference was identified by both artificially mixing urine samples with this cream and comparing the results obtained using the benzethonium chloride method with those obtained using the pyrogallol red method.
BACKGROUND: Gestational hypothyroidism has been shown to be associated with adverse pregnancy outcomes as well as adverse outcomes for the child. Thyroid hormones concentrations change in gestation, especially within the...BACKGROUND: Gestational hypothyroidism has been shown to be associated with adverse pregnancy outcomes as well as adverse outcomes for the child. Thyroid hormones concentrations change in gestation, especially within the first trimester, so the results of thyroid function test often are outside non-pregnant reference ranges. The objective of this study was to establish the first trimester reference ranges for thyroid stimulating hormone (TSH) and free thyroxine (FT4) for pregnant women in Barcelona (Spain). METHODS: It was a prospective study in which 673 women were recruited during their first trimester of gestation (8-13 weeks). Serum TSH, FT4 and antithyroid peroxidase antibodies (TPOAb) were measured with Atellica IM 1600 (Siemens Healthineers). After excluding 418 women, the reference ranges for TSH and FT4 were calculated by the 2.5th and 97.5th percentiles. Potential variables examined in this study were age, body mass index (BMI), ethnicity, iodine supplementation and smoking habit. RESULTS: The reference ranges established on the Atellica IM 1600 for the first trimester pregnancy in our population were 0.111 to 4.291 mIU/L for TSH and 11.45 to 17.76 pmol/L for FT4. No significant differences were found in thyroid hormones concentrations regarding maternal age (≤30 years vs >30 years) ( = .117), iodine supplementation ( = .683) and smoking habit ( = .363). The prevalence of TPOAb was estimated at 10.0%. CONCLUSIONS: We found that in our local population, the optimal TSH upper reference limit in the first trimester of gestation was 4.3 mIU/L, similar to that proposed by de ATA-2017 guideline (4.0 mIU/L).
Radley A, Beer L, Rushdi D
… +9 more, Close H, McBurney S, Mackenzie A, Gourlay A, Barnett A, Grant A, Greig N, Dow E, Sutherland C
Ann Clin Biochem
· 2024 Jul · PMID 37996254
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BACKGROUND: Point-of-care (POC) analysers in community settings can provide opportunistic and regular HbA1c monitoring. Community pharmacies in NHS Scotland are utilised by populations at greatest risk of type two diabet...BACKGROUND: Point-of-care (POC) analysers in community settings can provide opportunistic and regular HbA1c monitoring. Community pharmacies in NHS Scotland are utilised by populations at greatest risk of type two diabetes (T2D). This study describes initial development of an HbA1c pathway using a POC analyser in community pharmacies. METHODS: The Abbott Afinion analyser was compared in (i) NHS Tayside's Blood Sciences Service and (ii) community pharmacies from four Scottish Health Boards. A side by side comparison with standard operating procedures for HbA1c quantification using 80 T2D patient venous samples. The machine was implemented into 11 community pharmacies and 144 samples obtained from patients for comparison to their recent laboratory HbA1c. Four focus groups examined themes around the intervention and an exit questionnaire was administered. RESULTS: Laboratory assessment verified the efficacy of the POC test machine. The value for level 1 quality control was 44 mmol/mol and the mean during testing 42.7 mmol/mol. The greatest percent coefficient of variation (cv) was within-run for both levels of quality control material, at a value of 1.63% and 1.62%, respectively. The analyser performed robustly within the pharmacy assessment, with a mean difference of 1.68 and a standard deviation of 0.71 (CV 0.423). Patients with T2D reported positive experiences of using a pharmacy. The focus groups identified an appreciation of the convenience of pharmacies and of the longitudinal relationships with pharmacy staff. CONCLUSION: POC HbA1c analysers can be successfully established in community pharmacies. The target patient group responded positively to the opportunity to use a pharmacy service.
Holmes J, Higginson R, Geen J
… +1 more, Phillips A
Ann Clin Biochem
· 2024 May · PMID 37944994
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BACKGROUND: Acute kidney injury (AKI) is a global health issue known to cause avoidable harm and death. Improvement in its prevention and management is therefore considered an important goal for the health-care sector. T...BACKGROUND: Acute kidney injury (AKI) is a global health issue known to cause avoidable harm and death. Improvement in its prevention and management is therefore considered an important goal for the health-care sector. The work here aimed to develop a tool which could be used to robustly and reliably measure, monitor, and compare the effectiveness of health-care interventions related to AKI across the Welsh NHS, a mechanism which did not exist previously. METHODS: Using serum creatinine (SCr) as a biomarker for AKI and a validated national data-set collected from the all Wales Laboratory Information Management System, work involved applying Donabedian's framework to develop indicators with which to measure outcomes related to AKI, and exploring the potential of statistical process control (SPC) techniques for analysing data on these indicators. RESULTS: Rate of AKI incidence and 30-day AKI-associated mortality are proposed as valid, feasible indicators with which to measure the effectiveness of health-care interventions related to AKI. The control chart, funnel plot, and Pareto chart are proposed as appropriate, robust SPC techniques to analyse and visualise variation in AKI-related outcomes. CONCLUSIONS: This work demonstrates that routinely collected large SCr data offer a significant opportunity to monitor and therefore inform improvement in patient outcomes related to AKI. Moreover, while this work concerns utilisation of SCr data for improvement in AKI strategies, it is a proof of concept which could be replicated for other routinely collected clinical laboratory data, to improve the prevention and/or management of the conditions to which they relate.
BACKGROUND: Cell-free DNA (cfDNA) is free DNA found in circulating blood that originates from apoptosis or necrosis, and elevated cfDNA concentrations have been reported in cancers and other diseases. METHODS: In this st...BACKGROUND: Cell-free DNA (cfDNA) is free DNA found in circulating blood that originates from apoptosis or necrosis, and elevated cfDNA concentrations have been reported in cancers and other diseases. METHODS: In this study, the concentrations and fragment distributions of plasma cfDNA were preliminary investigated in elderly ( = 1) and paediatric ( = 1) patients with acute promyelocytic leukaemia (APL) treated with arsenic trioxide (ATO). RESULTS: A slight increase in cfDNA concentrations was observed in the APL patients compared with healthy controls. The change in plasma cfDNA concentrations corresponded to the change in plasma arsenic concentrations during ATO treatment. The fragment distribution pattern did not differ before and during treatment. Three ladder fragments were observed in part of the cfDNA in the second consolidation therapy in an elderly APL patient and the first consolidation therapy of a paediatric APL patient, while two fragments were observed in all other treatment periods. Moreover, APL-related gene mutations were successfully genotyped from plasma cfDNA by using polymerase chain reaction-based methods and these results are consistent with those from leukocytes. CONCLUSION: This study is the first to report the concentrations and fragment patterns of cfDNA from APL patients treated with ATO. The results suggested that plasma cfDNA concentration in APL patients increased with ATO treatment and that cfDNA is released mainly via neutrophil extracellular traps (and/or necrosis) in addition to apoptosis. To confirm whether cfDNA concentrations and fragment patterns can be used as a biomarker for APL treated with ATO, further accumulative data are needed.
BACKGROUND: The incidence, predictors, and association of cardiac troponin with mortality in hospitalized COVID-19 were not adequately studied in the past and were also not reported from an Indian hospital. METHODS: In t...BACKGROUND: The incidence, predictors, and association of cardiac troponin with mortality in hospitalized COVID-19 were not adequately studied in the past and were also not reported from an Indian hospital. METHODS: In this retrospective cohort study, the cardiac troponin of 240 hospitalized COVID-19 patients was measured. The incidence, predictors, and association of elevated cardiac troponin with in-hospital mortality were determined among hospitalized COVID-19 patients. RESULTS: The cardiac troponin was elevated in 12.9% (31/240) of the patients. The troponin was elevated in the patients in the older age group (64 years vs. 55 years, = .002), severe COVID-19 illness (SpO2 < 90%) (93.5% vs. 60.8%, < .001), low arterial oxygen saturation (SpO2) (80% vs. 88%, = .001), and low PaO2/FiO2 ratio ( < .0001). The patients with elevated cardiac troponin had elevated total leukocyte counts (TLC) ( = .001), liver enzyme ( = .025), serum creatinine ( = .011), N-terminal-Pro Brain natriuretic peptide ( < .0001), and d-dimer ( < .0001). The majority of the patients with elevated cardiac troponin were admitted to the intensive care unit (90.3% vs. 51.2%; < .0001), were on a ventilator (61.3% vs. 21.5%; < .0001), and had higher mortality (64.5% vs. 19.6%; < .0001). The Kaplan-Meir survival analysis showed that the patients with elevated troponin had worse survival ( log-rank<.0001). Age, NT-ProBNP, d-dimer, and ventilator were the predictors of elevated troponin in multivariate logistic regression analysis. The Cox-regression analysis showed a significant association between elevated cardiac troponin and in-hospital mortality (adjusted hazard ratio 2.13; 95% confidence interval [CI] 1.145-3.97; = .017). Two-thirds (65%) of patients with elevated cardiac troponin died during their hospital stay. CONCLUSIONS: COVID-19 patients with elevated cardiac troponin had severe COVID illness, were more commonly admitted to an intensive care unit, were on a ventilator, and had high in-hospital mortality.
Makhlouf R, Fendri S, Jallouli D
… +5 more, Labiadh Z, Fritis L, Chaabouni K, Elleuch A, Ayadi FM
Ann Clin Biochem
· 2024 May · PMID 37921518
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INTRODUCTION: The pneumatic tube system (PTS) is an automated and fast modality of transportation of biological samples, but it has been reported to induce preanalytical errors. AIM: To study the influence of transportat...INTRODUCTION: The pneumatic tube system (PTS) is an automated and fast modality of transportation of biological samples, but it has been reported to induce preanalytical errors. AIM: To study the influence of transportation by PTS on biochemistry tests which are particularly sensitive to haemolysis and atmospheric pressure variation. MATERIALS AND METHODS: We compared laboratory results of arterial blood gas, sodium, potassium, chloride, lactate dehydrogenase, aspartate aminotransferase, alanine aminotransferase, glucose and haemolysis index of samples conveyed simultaneously by PTS and by courier. RESULTS: We recruited 30 patients from the sampling room and 40 patients from the intensive care unit. Transport through PTS resulted in a significant increase in aspartate aminotransferase and potassium without exceeding the limits of acceptability. Potassium was significantly more increased for samples transported in a higher speed line ( = .048) but without exceeding the limits of acceptability. No significant impact was noted on haemolysis indices. The pO variations due to PTS transportation exceeded the limit of acceptability with significant intra-individual variations. CONCLUSION: Our PTS is validated for biochemistry tests results. It reduces turnaround times without affecting sample quality. However, the interpretation of arterial blood gas results should be careful for samples transported by PTS.
Stevic I, Bolsover J, Moore R
… +1 more, Bhayana V
Ann Clin Biochem
· 2024 May · PMID 37903217
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BACKGROUND: Delayed time from collection to centrifugation may cause erroneously high lactate levels in vitro (from continued blood cell metabolism under anaerobic conditions in the collection tube) if not collected in a...BACKGROUND: Delayed time from collection to centrifugation may cause erroneously high lactate levels in vitro (from continued blood cell metabolism under anaerobic conditions in the collection tube) if not collected in appropriate collection devices, consequently increasing the risk for inappropriate patient care or harm. We undertook a study to determine the turnaround time for lactate testing in a tertiary care setting and also performed short- and long-term lactate stability studies in blood collected in sodium fluoride/potassium oxalate (NaF/KOx) collection tubes. METHODS: The hospital lab information system was mined for 6 months to determine patient samples that may have exceeded the time from collection-to-receival in lab of 15-min. Lactate stability was evaluated in unspun NaF/KOx collection tubes at 15 min intervals for to 2 h; and separately at 2, 6, 12, 24, and 48-h post-collection. RESULTS: A total of 8,929 plasma samples were collected in 6 months, and 1/3 were not received in the lab within 15 min from collection. In NaF/KOx additive, lactate levels had minor increases over 2 h, and incremental increases at an average rate of 0.0035 mmol/L/h over 48 h with maximum increase of 9.8% at 48 h. However, the average change across all time points were within local allowable performance goals (at ≤4 mmol/L ± 0.5 mmol/L; at >4 mmol/L ± 12%). CONCLUSION: A small proportion of lactate specimens may experience delay in processing. Although lactate levels may incrementally increase over 48-h at room temperature in unspun NaF/KOx collection tubes, the changes may not be clinically impactful.
Ann Clin Biochem
· 2024 May · PMID 37845044
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BACKGROUND: Lipoprotein(a) (Lp(a)) is now established as a causal risk factor for cardiovascular disease (CVD) and accurate laboratory measurement is of pivotal importance in reducing Lp(a) associated risk. The consensus...BACKGROUND: Lipoprotein(a) (Lp(a)) is now established as a causal risk factor for cardiovascular disease (CVD) and accurate laboratory measurement is of pivotal importance in reducing Lp(a) associated risk. The consensus statement by HEART UK in 2019 included recommendations to improve standardisation of clinical laboratory measurement and reporting of Lp(a). METHODS: A 16 question, electronic audit survey was circulated to 190 accredited clinical biochemistry laboratories to assess the adoption of these recommendations in the UK. RESULTS: Responses were received from 65 of 190 laboratories (34%). Only 5 (8%) did not offer Lp(a) measurement. Of those providing the test, 23% (n = 14) offered an in-house service (IHS), the remaining laboratories (77%; n = 46) used an external referral service (ERS). The majority (10 of 14 or 71%) of IHS laboratories responded with details of their method, stating whether it minimised sensitivity to the effect of Lp(a) isoform size and used calibrators certified for traceability to the WHO/IFCC reference material, however, only a minority ERS laboratories (13 of the 46 or 28%) were able to specify the method used by their referral laboratory. Of the laboratories who specified their reporting units, 6 of 10 IHS and 7 of 23 ERS laboratories reported in nmol/L. Among the 60 laboratories who responded, the HEART UK recommendations appear to have been adopted in full by only 3 IHS laboratories. CONCLUSIONS: Further efforts are needed to standardise the measurement and reporting of Lp(a) so that results and interpretation are comparable across clinical biochemistry laboratories in the UK.
Loh TP, Cooke BR, Tran TCM
… +6 more, Markus C, Zakaria R, Ho CS, Theodorsson E, Greaves RF, IFCC Working Group on Method Evaluation Protocols (WG-MEP)
Ann Clin Biochem
· 2024 Jan · PMID 37838926
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Reporting a measurement procedure and its analytical performance following method evaluation in a peer-reviewed journal is an important means for clinical laboratory practitioners to share their findings. It also represe...Reporting a measurement procedure and its analytical performance following method evaluation in a peer-reviewed journal is an important means for clinical laboratory practitioners to share their findings. It also represents an important source of evidence base to help others make informed decisions about their practice. At present, there are significant variations in the information reported in laboratory medicine journal publications describing the analytical performance of measurement procedures. These variations also challenge authors, readers, reviewers and editors in deciding the quality of a submitted manuscript. The International Federation of Clinical Chemistry and Laboratory Medicine Working Group on Method Evaluation Protocols (IFCC WG-MEP) developed a checklist and recommends its adoption to enable a consistent approach to reporting method evaluation and analytical performance characteristics of measurement procedures in laboratory medicine journals. It is envisioned that the LEAP checklist will improve the standardisation of journal publications describing method evaluation and analytical performance characteristics, improving the quality of the evidence base that is relied upon by practitioners.
Ann Clin Biochem
· 2024 May · PMID 37789002
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BACKGROUND: Serum copper and zinc are measured to assess deficiency and toxicity. Atomic absorption spectrophotometry and mass spectrometry methods are expensive and require highly trained staff. Colorimetric assays are...BACKGROUND: Serum copper and zinc are measured to assess deficiency and toxicity. Atomic absorption spectrophotometry and mass spectrometry methods are expensive and require highly trained staff. Colorimetric assays are available from Randox which are inexpensive and can be automated. We validated serum copper and zinc colorimetric assays on the Binding Site Optilite analyser including comparison with flame atomic absorption spectrophotometry (FAAS) and inductively coupled plasma-mass spectrometry (ICP-MS). METHODS: Accuracy, imprecision, lower limit of quantitation, and linearity were ascertained. The impact of triglycerides, bilirubin, nickel, and iron on assay performance was also investigated. Comparison of results from colorimetric analysis of patient and external quality assurance samples with those obtained by FAAS and ICP-MS was undertaken. RESULTS: Intra-, and inter-assay imprecision was <9%. Serum copper and zinc assays were linear between 1.8-35.6 and 2.3-45.7 µmol/L, respectively. Agreement was good between colorimetry and FAAS (intercept = -0.7, slope = 1.04) and ICP-MS (intercept = 0.6, slope = 0.99) for serum copper in patients' samples. For serum zinc, agreement was poor between colorimetry and FAAS (intercept = 2.2, slope = 0.87) and ICP-MS (intercept = 1.9, slope = 0.98) in patients' samples. There was a poor concordance in assessment of hypozincaemia between colorimetry and FAAS/ICP-MS. CONCLUSION: The Randox colorimetric assay for serum copper on the Optilite is simple to perform, has a short analysis time, and measured concentrations compare well with FAAS and ICP-MS. Due to poor agreement with FAAS and ICP-MS, colorimetry is not suitable for the measurement of serum zinc.