TriNetX, a rapidly growing global network of anonymized patient data, enables clinical researchers to perform large-scale retrospective cohort studies. However, its functionality for querying laboratory data outcomes is significantly constrained, as it only provides the results of the most recent test within a specified observation period. Consequently, the platform is not optimized for analyzing laboratory data collected at multiple time points during an observation period. This paper introduces innovative, data-informed solutions to address these limitations, offering practical guidance for researchers aiming to leverage TriNetX for examining clinical laboratory data.

This case report describes a patient with uric acid kidney stones. Alkalization therapy using mainly potassium citrate is the first-choice treatment. When hyperuricosuria > 4 mmol/24 hours is present, xanthine oxidase inhibitors are added. It implies that accurate urine uric acid measurement is of high importance. Uric acid was measured in a 24-hour collection and a second-morning sample. Urine uric acid was measured after sample alkalization to pH > 6.5 and heating to 56 °C for 10 minutes, and for educational reasons without sample treatment. The uric acid excretion in the sample without alkalization in the 24-hour collection was 2.436 mmol, after alkalization, the excretion was 4.650 mmol/24 hours. Sample alkalization led to a prescription for xanthine oxidase inhibitor medication that is indicated as the second-line therapy when hyperuricosuria > 4 mmol/24 hours is present. This case study shows how the correct preanalytical phase is essential for medical decision-making.

The study aims to present a case study of a patient with supratherapeutic serum gentamicin concentration. An 83-year-old male was admitted to the Department of Internal Medicine for persistent loss of appetite, decompensated heart failure, and pneumonia. He was treated with 240 mg gentamicin daily alongside ampicillin/sulbactam penicillin antibiotic. The trough gentamicin concentrations and estimated glomerular filtration rate from creatinine (eGFRcrea) and cystatin C (eGFRcys) were performed. The patient had the supratherapeutic trough gentamicin concentration of 2.5 mg/L. eGFRcrea was 62 mL/min/1.73m and eGFRcys was 25 mL/min/1.73m. The difference between eGFRcrea and eGFRcys was 148%. Falsely high eGFRcrea in elderly patient led to the supratherapeutic gentamicin concentration even after the standard 240 mg gentamicin dose.

Thyroid function tests (TFTs) - thyroid stimulating hormone (TSH), total triiodothyronine (T3), total thyroxine (T4), free triiodothyronine (FT3), free thyroxine (FT4), thyroid peroxidase antibodies (anti-TPO), thyroglobulin antibodies (anti-Tg), TSH receptors antibodies (anti-TSHR), and thyroglobulin (Tg) - are used to diagnose thyroid disorders and are crucial biomarkers for monitoring and managing thyroid cancer. The 2022 national survey results revealed that thyroid function testing is not standardized among Croatian medical-biochemistry laboratories. Laboratories follow individual protocols at each testing stage, from patient preparation to result reporting. To address this, the Working group for laboratory endocrinology of the Croatian society of medical biochemistry and laboratory medicine has developed recommendations based on the latest national and international guidelines, research and the authors' expert opinion. The document aims to standardize all phases of thyroid function testing, with 7 preanalytical, 12 analytical, and 8 postanalytical recommendations, each supported by expert explanations. While primarily directed at Croatian laboratory professionals, this document is also relevant to other healthcare professionals managing thyroid-related health issues.

Primary Sjögren's syndrome (pSS) is a chronic autoimmune disease affecting exocrine glands and is frequently accompanied by depression and anxiety. Proinflammatory cytokines, particularly interleukin 6 (IL-6), have been implicated in the pathogenesis of both pSS and mood disorders. This study aimed to assess the association between inflammatory markers, disease activity, and psychological symptoms in patients with pSS.

Cardiac biomarkers may help diagnose and monitor different neonatal conditions, but their concentrations are still underexplored in common pathologies diagnosed within the first day. This study compared N-terminal pro b-type natriuretic peptide (NT-proBNP), high sensitivity troponin I (hs-TnI), creatine kinase (CK), and its isoenzyme creatine kinase-myocardial band (CK-MB) concentrations and activities, measured within the first 24 hours (h) postpartum, between the healthy term neonates and those with jaundice, perinatal infection, transient neurological abnormalities (TNA), and heart ultrasound abnormalities.

High-density lipoprotein (HDL) particles are key participants in reverse cholesterol transport. Cholesterol efflux capacity (CEC) and apolipoprotein A1 (Apo A1) are HDL-related biomarkers often used to evaluate HDL particle functionality and quantity. This study aimed to assess the correlation between CEC and Apo A1 concentrations and explore whether methodological aspects influence the correlation results.

Atherosclerosis is an active interaction between lipoproteins and inflammatory cells. Monocytes and macrophages are the most important immune cells involved in the process of atherosclerosis. They interact with atherogenic lipoproteins, in particular low density lipoprotein (LDL) cholesterol and lipoprotein(a) (Lp(a)). The increased concentration of the LDL cholesterol and Lp(a) accelerates the polarization of monocytes and macrophages toward proinflammatory phenotype and the formation of the foam cells. These cells then release large quantities of inflammatory cytokines that stimulate the oxidation of atherogenic lipoproteins that are even more atherogenic and contribute to the formation of foam cells and the secretion of the pro-inflammatory cytokines, thus creating a vicious circle. Surface marker C-C chemokine receptor type 2, expressed on monocytes/macrophages, enables their adhesion and migration into the subendothelial layer. The rupture of the atherosclerotic plaque on one hand, and the ability of the oxidized LDL cholesterol and Lp(a) to trigger arterial thrombosis by different mechanisms on the other hand, result in acute cardiovascular event. Here, we summarize the role of the monocytes and macrophages in atherosclerosis and explore the influence of LDL cholesterol and Lp(a) on monocytes and macrophages during the entire process of atherosclerosis, from its initiation to progression.

Spurious elevations in intact parathyroid hormone (iPTH) can lead to unnecessary interventions. We describe a dialysis patient who developed unexpectedly high iPTH concentrations months after total parathyroidectomy with forearm autotransplantation (TPTX-AT). Blood samples had been collected from the grafted forearm, resulting in falsely elevated iPTH values. Once the sample was collected from the non-grafted arm, iPTH concentrations normalized. This case highlights the importance of sampling site awareness in laboratory diagnostics and demonstrates how implementing a simple laboratory information system (LIS)-based protocol can prevent misinterpretation.

Hepcidin (Hep), a key regulatory hormone of iron (Fe) homeostasis, governs its absorption and storage, and is influenced by inflammation and Fe status. This study investigated serum Hep concentrations and their associations with Fe markers and inflammation in patients with sporadic colorectal cancer (CRC).

The ISO 15189:2022 standard considers both the robustness of analytical methods and the risk of erroneous results in the quality control plan (QCP) design. Westgard .'s nomogram recommends quality control (QC) rules based on sample run size to ensure that the maximum expected number of unreliable patient results remains below one. This study aimed to implement a standardized, risk-based QC strategy across multiple analyzers without integrated on board QC, ensuring practical quality assurance.

The alcohol dehydrogenase (ADH) method is commonly used to measure serum alcohol concentration (SAC) and plasma alcohol concentration (PAC) for the rapid detection of ethanol intoxication in emergency medical departments. Alcohol dehydrogenase methods are sometimes used in forensic laboratories as a preliminary screening test prior to confirmation by gas chromatographic (GC) methods. This review identifies critical factors affecting results of ADH methods of analysis including clinical reliability and forensic defensibility. Key considerations include intra-analytical factors (method chemistry, calibration, analytical performance, interferences, calibrator stability, and sample matrix effects) and post-analytical factors (measurement units, reference ranges, performance specifications, uncertainty budget, medical decision levels, legal intoxication thresholds, ADH-GC agreement, and SAC/PAC to blood alcohol concentration (BAC) conversion). The yeast ADH method demonstrates high selectivity for ethanol with no assay-specific bias, and measurement error and uncertainty meet regulatory standards. However, ADH methods are prone to interferences, particularly from lactate dehydrogenase/lactic acid (LD/LA), leading to potential false positive results. Free hemoglobin (hemolysis) is another problem with ADH methods introducing a negative bias. When results provided by hospital laboratories are interpreted in a legal context, care is needed because ethanol concentrations in plasma/serum are about 15% higher than in whole blood (range 10-20%). Although less important in clinical practice, these differences are important to consider in a forensic context. The ADH method is not inherently a forensic assay, but these limitations can be mitigated by refining laboratory procedures and standardizing the assay methodology and quality control, thus strengthening forensic reliability and boosting confidence in the analytical results.

This study aimed to investigate potential benefit of personalized reference intervals (prRIs) by conducting a four-month observation of a woman with SARS-CoV-2 reinfection. Two types of prRIs were calculated: one derived from the population biological variation (BV) data provided by the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) biological variation database (prRIs_), and the other derived from individual variation data (prRIs_). These were subsequently compared. A total of 110 test results encompassing complete blood count (CBC) and leukocyte differential counts from the case were assessed according to the limits of prRIs_, reference change values (RCVs_) and the population-based reference intervals (popRIs). In instances where limited historical health data are available (N ≤ 3), the application of prRIs_ was recommended over prRIs_. The prRIs_ and RCVs_ identified a greater number of potential clinical pathological change compared to popRIs (the ratio of potential abnormal values to total test values: prRIs_ 22/110, RCVs_ 25/110, popRIs 2/110, respectively). The findings suggest that the use of prRIs can be advantageous in clinical settings and is worthy of broader adoption. However, it is essential to choose an appropriate calculation method tailored to the specific clinical context.

Acute abdominal pain accounts for 7-10% of all emergency department visits. Appendicitis, being one of the leading causes of acute abdominal surgery, poses significant diagnostic challenges. Negative appendectomy rates can be as high as 40%, while complications occur in more than 90% if the diagnosis is missed during the initial examination. Therefore, more effective preoperative screening is required for patients with suspected appendicitis. Recent studies suggest that novel biomarkers, particularly leucine-rich alpha 2-glycoprotein and calprotectin, may improve the early and accurate diagnosis of acute appendicitis by demonstrating high specificity and sensitivity, respectively. Unlike C-reactive protein, the production of leucine-rich alpha 2-glycoprotein 1 and calprotectin takes place at the site of inflammation. As a result, their raised concentrations might be evident early in a disease, possibly before other common markers of inflammation start to rise. This literature review aims to assess the potential role of leucine-rich alpha 2-glycoprotein 1 and calprotectin as diagnostic biomarkers in patients with suspected acute appendicitis, acknowledging the need for additional data to fully assess their diagnostic accuracy.

25-hydroxyvitamin D (25-OH-D) is essential for calcium homeostasis and bone health, with increasing evidence suggesting associations with non-skeletal diseases. However, the lack of consensus on optimal concentrations and laboratory variability has led to clinical uncertainty and excessive testing. This study evaluates the impact of demand management strategies and revised cut-off points on test volumes, unperformed determinations, and cost savings.

Serum neuron specific enolase (NSE) is used as neuroendocrine tumor and central nervous system damage marker. It is present in variable concentrations in erythrocytes and hemolysis interferes in serum NSE quantification. Our aim was to develop a correction formula for moderate hemolysis, based on repeated patient samples instead of artificial sample doping with hemolysates.

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.

The study of Cristelli 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.

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.

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 ( hypokalemia) can be the first and only symptom in patients with VIP-secreting neuroblastoma which can result in delayed diagnosis of neuroblastoma.