Preanalytical Errors in Clinical Laboratory Testing at a Glance: Source and Control Measures.

The accuracy of diagnostic results in clinical laboratory testing is paramount for informed healthcare decisions and effective patient care. While the focus has traditionally been on the analytical phase, attention has shifted towards optimizing the preanalytical phase due to its significant contribution to total laboratory errors. This review highlights preanalytical errors, their sources, and control measures to improve the quality of laboratory testing. Blood sample quality is a critical concern, with factors such as hemolysis, lipemia, and icterus leading to erroneous results. Sources of preanalytical errors encompass inappropriate test requests, patient preparation lapses, and errors during sample collection, handling, and transportation. Mitigating these errors includes harmonization efforts, education and training programs, automated methods for sample quality assessment, and quality monitoring. Collaboration between laboratory personnel and healthcare professionals is crucial for implementing and sustaining these measures to enhance the accuracy and reliability of diagnostic results, ultimately improving patient care.

The Laboratory and Clinical Perspectives of Magnesium Imbalance.

Magnesium (Mg2+) is a predominantly intracellular cation that plays significant roles in various enzymatic, membrane, and structural body functions. As a calcium (Ca2+) antagonist, it is imperative for numerous neuromuscular activities. The imbalance of body Mg2+  concentration leads to clinical manifestations ranging from asymptomatic to severe life-threatening complications. Therefore, the contribution of Mg2+ measurement regarding various laboratory and clinical aspects cannot be ignored. Mg2+ is often described as the forgotten analyte. However, its close relationship with body potassium (K+), Ca2+, and phosphate homeostasis proves that Mg2+ imbalance could co-exist as the root cause or the consequence of other electrolyte disorders. Meanwhile, several preanalytical, analytical, and postanalytical aspects could influence Mg2+ measurement. This review highlights Mg2+ measurement's laboratory and clinical issues and some analyte disturbances associated with its imbalance. Understanding this basis could aid clinicians and laboratory professionals in Mg2+ result interpretation and patient management.

Serum free light chains: diagnostic and prognostic value in multiple myeloma.

BACKGROUND: Measurement of serum free light chains (FLCs) has recently become available for the diagnosis and monitoring of patients with plasma cell dyscrasias. The aim of this study was to investigate the performance of the serum FLC assay as a tumour marker by comparing FLC concentrations with serum protein electrophoresis (PE) results in the diagnosis of multiple myeloma (MM). In addition, we also evaluated the prognostic value of the baseline serum FLC ratio in patients with MM. METHODS: We measured FLC concentrations and calculated the kappa/lambda (kappa/lambda) FLC ratios for three groups (control, polyclonal gammopathy and MM). RESULTS: The FLC ratio at a cut-off threshold of 2.0 showed higher sensitivity and specificity compared with serum electrophoresis for the diagnosis of MM. We used the median FLC ratio of >57.5 and <0.04 for kappa and lambda secretors, respectively, for assessing survival. Survival was 30 months in patients with the kappa/lambda ratio of >57.5 and <0.04 compared to 47 months in patients with the ratio <57.5 and >0.04, indicating that more abnormal serum FLC ratios are associated with poorer survival (p<0.011). CONCLUSIONS: Despite the limitations of the assay, the results of our study indicate that the FLC assay in combination with serum PE has an increased sensitivity in the diagnosis of MM. Also, baseline measurement of the kappa/lambda ratio provides prognostic information in these same patients.

Performance evaluation of the Arkray Adams HA-8160 HbA1c analyser

BACKGROUND: HbA1c measurement is currently routinely used to predict long term outcome of diabetes, thus playing a fundamental role in the management of diabetes. The relationship between HbA1c value and long term diabetic complications has been established by a randomised control Diabetes Control and Complications Trial (DCCT) which used high performance liquid chromatography (HPLC) as a reference method for HbA1c assay. To ensure that HbA1c results from a variety HbA1c assay methods are similar to the DCCT values, the American Diabetes Association (ADA) recommended that all laboratories should use methods certified by the National Glycohemoglobin Standardization Programme (NGSP) with interassay coefficient variation (CV) of < 5% (ideally < 3%). The International Federation of Clinical Chemistry (IFCC) working group on HbA1c standardisation has set a CV < 2.5% as a criteria for its reference laboratories. OBJECTIVES: To evaluate the performance of Arkray Adams HA-8160 HbA1c analyser which uses a cation exchange HPLC method and its correlation to HbA1c assay on Cobas Integra 800 which is an immunoturbidimetric method. METHODS: For the imprecision study, patient samples and control material of two levels were analysed on HA-8160 analyser 20 times in a single run (within-run imprecision) and twice a day on five consecutive days (between-run imprecision). For the recovery study, two samples each with high and low values were selected and mixed in ratios of 1:3, 1:1 and 3:1, and were analysed by HA-8160. Sixty samples were analysed by both Cobas Integra 800 and HA-8160 for method comparison study. Ten uraemic samples and ten thalassaemic samples were assayed on Cobas Integra 800 and HA 8160 for interference study. RESULTS: Within-run CVs were 0.6% and 0.7% for medium and high value samples respectively, 0.6% and 0.7% for low and high level controls respectively. Between-run CVs were 0.5% and 0.4% for medium and high value samples respectively, 0.5% and 0.6% for low and high level controls respectively. The mean recovery was 100.1%. A good correlation between the 2 methods (Adams = 1.00 Cobas - 0.11, r = 0.98) was observed. CONCLUSIONS: The Akray Adams HA-8160 HbA1c analyser performed within the target CV of < 2.5% and showed a good correlation with the Cobas Integra 800.