Annals of Clinical Biochemistry

BACKGROUND: Parametric regression analysis is widely used in methods comparisons and more recently in checking the concordance of test results following receipt of new reagent lots. The greater frequency of reagent-lot evaluations increases pressure to detect bias with smallest possible sample sizes (i.e. smallest consumption of time and resources). This study revisits bias detection using the joint slope, intercept confidence region as an alternative to slope and intercept confidence intervals...

BACKGROUND: It is important that blood glucose concentrations be accurately and conveniently measured in infants. However, especially in the early neonatal period, point-of-care testing devices used for adults may not accurately measure blood glucose concentrations in neonates. METHODS: In Study 1, the accuracy of neonatal whole-blood glucose measurements was evaluated for the existing glucose analyser Glutest Mint® (hereinafter MINT1; Sanwa Kagaku Kenkyusho, Nagoya, Japan) by comparing the data with reference blood glucose concentrations...

BACKGROUND: Serum total testosterone (T) decreases postprandially. Postprandial salivary testosterone (SalT) responses, however, have not been studied. We report on the effect of glucose ingestion on fasting SalT concentrations. OBJECTIVE: To investigate the effect of oral glucose ingestion on fasting SalT. METHODS: Salivary and blood samples were collected between 09.00 and 09.30 and two hours after a 75g oral glucose load in 32 men with mean (standard deviation) age of 52 (5...

PURPOSE: The primary goal was to estimate reference values of parathyroid hormone (PTH) in very low birth weight infants without severe neonatal morbidity. A secondary objective was to assess the relationship between PTH serum levels and selected laboratory markers of bone metabolism. METHODS: 92 infants with birth weight less than 1500 g met the inclusion criteria of the study. Serum levels of PTH, 25-hydroxyvitamin-D [25(OH)D], C3-epi-25(OH)D, total calcium, phosphorus, and alkaline phosphatase, and urinary levels of calcium, phosphorus, and creatinine were examined on day 14 and subsequently every two weeks till discharge...

No abstract text is available yet for this article.

Background There is a lack of standardisation of reference intervals (RIs) for ferritin across laboratories, particularly for postmenopausal women. Depending on the RI used, there can be more than a 4-fold difference in the upper limit of normal between laboratories, resulting in potential misinterpretation. Methods This retrospective study used a large dataset of blood test results from 25,425 healthy participants aged 18 to 97 over a 7-year period. Exclusion criteria were used to screen out individuals with conditions known to affect iron metabolism or raise ferritin as part of the acute phase response...

BACKGROUND: Carnitine is essential for fatty acid metabolism. Free carnitine (FCA) is excreted in the urine in the glomerulus, but is partly reabsorbed by a carnitine transporter. The mechanism underlying the decrease in serum carnitine level during pregnancy is unclear. OBJECTIVE: To investigate whether low carnitine level is associated with increased renal excretion in pregnant women. METHODS: We recruited 43 healthy pregnant and 25 non-pregnant women...

Robust preanalytical and analytical processes are critical for the detection of cryoproteins. There is significant variation in practice in the detection, analysis and reporting. A survey in 2007 of 137 laboratories participating in the UK National External Quality Assessment Service (UK NEQAS) (6) quality control program showed significant variation in the laboratory processes which highlighted the need for standardisation of the detection, analysis and reporting of cryoglobulins.The first available EQA scheme aiming to harmonise practice for cryoprotein testing has been developed by UK NEQAS and laboratories should participate in an appropriate EQA scheme to fulfil requirements for ISO accreditation...

No abstract text is available yet for this article.

Background It is recommended that samples for plasma ammonia analysis are kept chilled and processed promptly as in vitro metabolism causes falsely elevated results. Rejection of unsuitable samples can cause delayed diagnosis and treatment of hyperammonaemia with potentially serious clinical consequences. The Metabolic Biochemistry Network (MetBioNet) hyperammonaemia guideline recommends analysis of samples not collected under ideal conditions and reporting with appropriate comments. An audit found that some laboratories did not follow this guidance...

BACKGROUND: Early diagnosis of thyroid cancer is hampered by the inability of fine-needle aspiration biopsy (FNAB) to accurately classify ∼30% of cases while preoperative cancer staging detects lymph nodal involvement in only half of cases. Liquid biopsy may present an accurate, non-invasive alternative for preoperative thyroid nodule assessment. Thyrotropin receptor (TSHR) mRNA, a surrogate marker for circulating cancer cells (CTC), may be an option for early detection of malignancy from peripheral blood, but requires methodological improvements...

Background Clinical laboratories frequently implement the same tests and internal quality control (QC) rules on identical instruments. It is unclear whether individual QC targets for each analyser or ones that are common to all instruments are preferable. This study modelled how common QC targets influence assay error detection before examining their effect on real-world data. Methods The effect of variable bias and imprecision on error detection and false rejection rates when using common or individual QC targets on 2 instruments was simulated...

No abstract text is available yet for this article.

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 2,902 newborns delivered at 22 to 41 weeks of GA or 264 to 4,642 g of BW after exclusion of those with congenital disorders...

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...

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...

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 [1]. Serum ketamine monitoring is becoming increasingly important where a sensitive method is required with a robust lower limit of quantitation. METHODS: Samples were prepared using protein precipitation or solid phase extraction. Ion suppression was investigated to assess sample preparation technique, followed by reverse phase chromatography coupled with tandem mass spectrometry to analyse extractions using a Waters Xevo TQ-s and associated Acquity chromatography systems...

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, i.e. 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...

No abstract text is available yet for this article.

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.