Biochemia medica最新文献

Neuroblastomas represent a diverse group of neuroblastic tumors characterized by variability in their clinical progression and degree of differentiation. In rare cases, patients with neuroblastoma may present with paraneoplastic syndromes, such as watery diarrhea, hypokalemia, and achlorhydria (WDHA syndrome), linked to the secretion of vasoactive intestinal peptide (VIP). We report a case of a 14-month-old girl presented with a three-week history of watery diarrhea and signs of dehydration with no other symptoms. The patient's medical history was unremarkable, and no medication use was reported. Venous blood gas analysis revealed a normal anion gap metabolic acidosis with severe hypokalemia. The patient was referred to our hospital 48 hours post-admission due to persistent hypokalemic metabolic acidosis, unresponsive to intravenous fluid therapy. The primary causes of normal anion gap metabolic acidosis in young children are gastrointestinal bicarbonate loss due to diarrhea and renal bicarbonate loss. Semi-quantitative urine organic acid analysis, reported 48 hours after admission, revealed increased vanillylmandelic acid (VMA) (89 mmol/mol creatinine) and homovanillic acid (HVA) (21 mmol/mol creatinine), raising the suspicion of a neuroblastoma. Subsequent analysis of an acidified urine sample confirmed a more than threefold increase in VMA, HVA, normetanephrine, norepinephrine, and 3-methoxytyramine concentrations. In addition, VIP was markedly elevated (1994 ng/L) in a blood sample. The diagnosis of neuroblastoma was confirmed through imaging and histological examination. This case illustrates that chronic diarrhea with metabolic dysregulation (e.g. hypokalemia) can be the first and only symptom in patients with VIP-secreting neuroblastoma which can result in delayed diagnosis of neuroblastoma.

The study of Cristelli et al. attempted to find fault with the rules suggested by Westgard Advisor software, claiming that implementing those rules did not improve the method performance. A fundamental misunderstanding of the utility and purpose of the analytical Sigma-metric and QC rules needs to be clarified.

Introduction: Small cell lung cancer (SCLC) is an aggressive malignant disease with poor survival outcomes. The aim of this study was to investigate leukocyte telomere length (LTL) and redox status parameters during chemotherapy and evaluate their prognostic potential based on the hypothesis that shorter LTL and oxidative stress burden correlate with poorer survival.

Materials and methods: This longitudinal study included 60 SCLC patients and 73 healthy controls. Leukocyte telomere length was measured by quantitative PCR (qPCR) method, while redox status parameters (MDA - malondialdehyde, IMA - ischemia-modified albumin, PON1 - paraoxonase 1, redox index) were determined by spectrophotometric methods before, after two and after four cycles of chemotherapy.

Results: All measured parameters showed significant differences between patients and controls, except the oxy-score (P < 0.001). Significant differences in IMA, PON1 and redox index were observed between SCLC patient groups at different time points (P < 0.001). Significant differences in IMA and PON1 were observed between SCLC survival groups, with higher values found in survivors after two chemotherapy cycles (P < 0.001). Redox index was the highest in the pre-chemo group (P = 0.019). Among patients who died, PON1 activity differed significantly between those who died within 2 months and after 4 months (P = 0.028). Kaplan-Meier analysis showed that LTL and PON1 were significant predictors of survival, with values below the 25th percentile associated with a higher risk of death.

Conclusions: Leukocyte telomere length and PON1 are potential prognostic biomarkers for SCLC survival, suggesting their potential use in non-invasive biomarker panels for improved patient stratification.

Introduction: Accurate measurement of urinary total protein (UTP) is crucial for diagnosing renal and systemic diseases. This study aims to comprehensively evaluate potential carryover scenarios in UTP testing using AU5800 biochemistry analyzer and to identify factors influencing assay accuracy.

Materials and methods: High-concentration quality control materials and pure water was used to evaluate specific sample probe carryover. Additionally, 24-hour mixed urine samples from patients were used to evaluate specific carryover from the reagent probe, mixbars, and cuvettes. For cumulative sample carryover evaluation, pure water was used as reagent and mixed serum as sample for continuous testing. During the process, 24-hour urine samples were interspersed, and UTP concentrations were measured at 0, 10, 20, and 30 minutes. Cumulative reagent carryover was evaluated by testing pure water sequentially with eight reagents sharing the same analytical unit and inner cuvettes as UTP, with UTP concentrations of 24-hour urine samples recorded at 0, 10, 20, and 30 minutes.

Results: Specific carryover from the sample probe, reagent probe, mixbars, and cuvettes was not detected during carryover evaluation of UTP testing. However, a significant cumulative reagent carryover of Immunoglobulin G (IgG) reagent was observed, while no cumulative sample carryover was identified.

Conclusions: The full range of possible carryover scenarios in UTP testing was evaluated using AU5800 biochemistry analyzer. Our data provide valuable references for evaluating carryover in laboratories, ensuring the accuracy and reliability of laboratory results.

Introduction: One of the critical points of the preanalytical phase is the patient's adherence to the required fasting duration before undergoing medical analysis. Although many laboratories have already protocols for blood-sample collection that require only a 6-hour fast, clinical guidelines remain unclear on this aspect, and fasting periods of 12 hours are sometimes still recommended. The aim of this study was to evaluate whether there are significant differences between the results obtained in patients' serum samples obtained post-fasting, 4 hours post-meal, and 6 hours post-meal for different predetermined parameters.

Materials and methods: 30 volunteers (16 females and 14 males) aged between 23 and 62 years were selected for this study. Each participant underwent an initial analysis after a 10-hour fast (baseline), a second analysis 4 hours after a controlled meal, and a third analysis 6 hours after the meal. The parameters studied correspond to previously selected biochemical, hematological, and coagulation tests. To assess if there are significant differences in the results obtained for each analyte, criteria based on the total allowable error (TEa) and the reference change value (RCV) were used.

Results: All parameters evaluated in this study met the criteria based on the RCV at both 4 and 6 hours, although some parameters did not meet TEa criteria.

Conclusions: The results obtained in this study demonstrated that a fasting period of 4 or 6 hours is sufficient to obtain reliable results. This could significantly improve the quality of life for patients undergoing analysis without compromising the quality of their results.

Hereby we describe a case of a 59-year-old female patient with persistently elevated high-sensitivity troponin I (hs-TnI) over the course of almost four years measured on Alinity i with the corresponding assay (Abbott Laboratories, Chicago, USA). The patient underwent multiple extensive cardiological evaluations, but none of them suggested acute or chronic cardiac damage. Therefore, interference in measurement was suspected by the attending cardiologist and a detailed, stepwise laboratory investigation was undertaken in the sample with initial hs-TnI result of 2077 ng/L. Serial sample dilutions (1:2,1:5,1:10) did not match the expected, calculated hs-TnI concentrations, yielding both huge positive biases (62, 109 and 139%, respectively) and absolute differences (639, 453 and 290 ng/L, respectively). Precipitation with polyethylene-glycol, pretreatment in heterophilic blocking tubes (HBT) and immunoglobulin G depletion yielded hs-TnI results below the assay's diagnostic cut-off (< 15.6 ng/L). Alternate hs-TnI immunoassays (Siemens Healthineers, Beckman Coulter and Snibe) and measurement with the high-sensitivity troponin T (hs-TnT) assay yielded results below assays' specific cut-off values. This investigation confirmed that results of hs-TnI obtained by the Abbott assay were spuriously elevated. Significant lowering of hs-TnI after HBT pretreatment indicated that heterophile antibodies are the most probable source of interference. Based on this finding, it was entered in the patient's medical record that future determinations of cardiac troponin should be performed with an alternate hs-TnI or hs-TnT assay. This case emphasizes that analytical interferences are usually immunoassay-dependent. Evaluation of laboratory results in the clinical context and close collaboration between laboratory and clinical staff is crucial for their recognition.

The family of antineutrophil cytoplasmic antibodies (ANCA) includes autoantibodies targeting proteins within the primary granules of neutrophils and lysosomes of monocytes. So far, proteinase 3 (PR3) and myeloperoxidase (MPO) are considered clinically relevant ANCA specificities. National recommendations for the assessment of ANCA are the outcome of the survey done by the Working group (WG) for laboratory diagnostics of autoimmune diseases of the Croatian Society of Medical Biochemistry and Laboratory Medicine (CSMBLM), where the diversity in the performance of ANCA testing and reporting among the laboratories in Croatia was observed. This document contains recommendations concerning the indications for ANCA testing, preanalytical, analytical and postanalytical issues, including rational algorithm and quality control assurance. The recommendations are based on the International consensus on ANCA testing and reporting as well as other relevant literature in order to help to harmonize ANCA testing. The aim of these recommendations is to improve and harmonize ANCA testing among laboratories in Croatia.

Creatine kinase (CK) activity has been generally considered as reliable blood marker for assessing muscle function, damage, and repair. However, the greatest challenge in the interpretation of CK activity remains the high variability in CK increase in relation to degrees of muscle cell damage or disturbance. Several known contributors to CK variability have been identified. The most important include the type of training, exercise intensity, gender differences, body composition, intra- and interindividual biological variability, as well as preanalytical and analytical considerations. Creatine kinase variability following different types of exercise reflects the complex interplay between exercise modality, intensity, individual physiology, and recovery strategies. High-intensity exercises, especially those involving eccentric muscle contractions, tend to produce more significant CK responses due to greater muscle fiber disruption. Gender differences in CK variability are pronounced, with men generally exhibiting higher CK activities following exercise compared to women. Creatine kinase variability is also closely linked to body composition, with muscle mass generally leading to higher CK activities post-exercise, while higher body fat may correlate with lower CK responses. Regarding preanalytical and analytical considerations, perhaps the greatest challenge in CK measurement is the limited sample stability, which should always be taken into consideration when analyzing CK activity in stored samples for research or clinical purposes. This review, through exploring all of the above-mentioned sources of CK variability, could facilitate the development of evidence-based practices for preventing overuse injuries, and promoting long-term athlete health and well-being.

For decades, bilirubin was thought to be merely a degradation product of the hem, a potentially toxic compound and a molecule with no specific physiological function. Recently, it has been discovered that bilirubin has a strong antioxidant effect and possesses molecular signalling, hormonal and immunomodulatory properties. Numerous studies show that moderately elevated serum bilirubin concentrations correlate with a lower risk of developing pathological conditions mediated by oxidative stress and inflammation. Low concentrations within the current reference interval have been shown to be a potential risk factor for various pathological conditions. It is to be expected that knowledge about bilirubin will lead to the determination of bilirubin concentration gaining new importance in diagnostics, for example as a prognostic marker, but also as a therapeutic molecule.

Introduction: A control chart based on Hotelling's T² multivariate statistics was used to monitor the quality of an immunoenzymatic assay for plasma levetiracetam. The chart incorporated a multi-level quality control (MLQC) system with three concentration levels of the analyte and included the analytical performance specification (APS) for therapeutic drug monitoring.

Materials and methods: Data were collected from March 1 to August 14, 2024, comprising 84 consecutive triplets of values for the three MLQC levels. The initial 59 triplets were used to estimate the variance-covariance matrix and vector of means (phase I). These estimates were then applied to calculate Hotelling's T² for the remaining 25 triplets (phase II). The pharmacokinetic model of Fraser was employed to derive the APS for levetiracetam, based on a twice-daily dosing scheme and a median half-life of 8 hours.

Results: The three MLQC levels showed significant correlations (r > 0.6) in both control phases. The Hotelling's T² control chart detected no out-of-specifications states (OC), compared to 12 OC signals from individual Levey-Jennings charts monitoring the MLQC levels separately. The integration of the APS into the Hotelling's T² chart provided additional insights into the process quality, and in two instances, it aligned with the OC signal from at least one of the Levey-Jennings charts.

Conclusions: Hotelling's T² multivariate chart is effective for internal quality control of laboratory tests. As MLQC data offer correlated information, this approach is advantageous over multiple individual univariate charts as it ensures the correct level of false positive and false negative alarms.