Clinical chemistry and laboratory medicine in Croatia: regulation of the profession

Heterogeneity exists across Europe in the definition of the profession of clinical chemistry and laboratory medicine and also in academic background of specialists in this discipline. This article provides an overview of the standards of education and training of laboratory professionals and quality regulations in Croatia. Clinical chemistry in Croatia is almost exclusively practiced by medical biochemists. Although term Medical biochemist often relates to medical doctors in other European countries, in Croatia medical biochemists are not medical doctors, but university degree professionals who are qualified scientifically. Practicing the medical biochemistry is regulated by The Health Care Law, The Law of the Medical Biochemistry Profession and The Law of the State and Private Health Insurance. According to the law, only medical biochemists are entitled to run and work in the medical biochemistry laboratory. University degree is earned after the 5 years of the studies. Register for medical biochemists is kept by the Croatian Chamber of Medical Biochemists. Licensing is mandatory, valid for 6 years and regulated by the government (Law on the Health Care, 1993). Vocational training for medical biochemists lasts 44 months and is regulated by the national regulatory document issued by the Ministry of Health. Accreditation is not mandatory and is provided by an independent, non-commercial national accreditation body. The profession has interdisciplinary character and a level of required competence and skills comparable to other European countries.     

Acquired hemophilia A secondary to SARS-CoV-2 pneumonia: a case report

The acquired hemophilia A (AHA) is a life-threatening condition. The incidence of AHA is extremely low, which requires a multidisciplinary approach to diagnosis and treatment. This is case report of 73-year-old man who presented with AHA secondary to severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) pneumonia. The patient had extensive skin bleeding and hematomas. In the coagulation screening tests activated partial thromboplastin time (APTT) was prolonged with normal prothrombin time (PT), which was indication for further investigation. The APTT in a mixing study with normal plasma did not correct so clotting factors inhibitors were suspected. With signs of bleeding, extremely low factor VIII (FVIII) activity (2%) and presence of FVIII inhibitors, AHA was diagnosed and treatment initiated. Patient was treated with factor eight inhibitor bypassing agent (FEIBA) for three days, followed by long-term corticosteroid and cyclophosphamide therapy. Malignant and autoimmune diseases as the most common causes of AHA were ruled out. The patient had a good response to therapy with gradual normalization of APTT and FVIII activity. To the best of our knowledge, the present case is the first reported case of de novo AHA after SARS-CoV-2 pneumonia. The diagnosis of AHA should be suspected in a patient with bleeding into the skin and mucous membranes without a previous personal and family history of bleeding, and with isolated prolonged APTT. It is important to investigate any isolated prolongation of APTT in cooperation with clinical laboratory experts.     

Exploration of Factors Affecting the Added Value of Test Subscores

Recently, interest in test subscore reporting for diagnosis purposes has been growing rapidly. The two simulation studies here examined factors (sample size, number of subscales, correlation between subscales, and three factors affecting subscore reliability: number of items per subscale, item parameter distribution, and data generating model) that affected the value of reporting subscores within the classical test theory framework. Results showed that a higher proportion of subscores of added value was related to lower correlation between subscales, more items per subscale, no guessing in responses, smaller variability in difficulty parameters, and matched average item difficulty and average examinee ability.     

Routing Strategies and Optimizing Design for Multistage Testing in International Large‐Scale Assessments

This study investigates the effect of several design and administration choices on item exposure and person/item parameter recovery under a multistage test (MST) design. In a simulation study, we examine whether number‐correct (NC) or item response theory (IRT) methods are differentially effective at routing students to the correct next stage(s) and whether routing choices (optimal versus suboptimal routing) have an impact on achievement precision. Additionally, we examine the impact of testlet length on both person and item recovery. Overall, our results suggest that no single approach works best across the studied conditions. With respect to the mean person parameter recovery, IRT scoring (via either Fisher information or preliminary EAP estimates) outperformed classical NC methods, although differences in bias and root mean squared error were generally small. Item exposure rates were found to be more evenly distributed when suboptimal routing methods were used, and item recovery (both difficulty and discrimination) was most precisely observed for items with moderate difficulties. Based on the results of the simulation study, we draw conclusions and discuss implications for practice in the context of international large‐scale assessments that recently introduced adaptive assessment in the form of MST. Future research directions are also discussed.     

Platelet satellitism in infectious disease?

Background

Platelet satellitism is a phenomenon of unknown etiology of aggregating platelets around polymorphonuclear neutrophils and other blood cells which causes pseudothrombocytopenia, visible by microscopic examination of blood smears. It has been observed so far in about a hundred cases in the world.

Case subject and methods

Our case involves a 73-year-old female patient with a urinary infection. Biochemical serum analysis (CRP, glucose, AST, ALT, ALP, GGT, bilirubin, sodium, potassium, chloride, urea, creatinine) and blood cell count were performed with standard methods on autoanalyzers. Serum protein fractions were examined by electrophoresis and urinalysis with standard methods on autoanalyzer together with microscopic examination of urine sediment. Erythrocyte sedimentation rate, blood culture and urine culture tests were performed with standard methods.

Results

Due to typical pathological values for bacterial urinary infection, the patient was admitted to the hospital. Blood smear examination revealed phenomenon, which has persisted for three weeks after the disease has been cured. Blood smears with EDTA as an anticoagulant had platelet satellitism whereas the phenomenon was not observed in tubes with different anticoagulants (Na, Li-heparin) and capillary blood.

Discussion

We hypothesize that satellitism was induced by some immunological mechanism through formation of antibodies which have mediated platelets binding to neutrophil membranes and vice versa. Unfortunately we were unable to determine the putative trigger for this phenomenon. To our knowledge this is the second case of platelet satellitism ever described in Croatia.Key words: blood platelets, thrombocytopenia, EDTA, urinary infection     

Anti-Müllerian hormone: a unique biochemical marker of gonadal development and fertility in humans

Anti-Müllerian hormone (AMH) is a glycoprotein belonging to the transforming growth factors (TGF-P). AMH plays a fundamental role in the regression of Müllerian ducts in male embryo. In its absence, Müllerian ducts develop into female inner reproductive organs. In boys, it is significantly produced in Sertoli cells of testes until puberty and then slowly decreases to residual values for the rest of the men's life. AMH serves as a biochemical marker of the presence of testes in cryptorchidic males. In females, AMH is secreted by granulosa cells of small follicles in the ovary. Serum values are almost undetectable during infancy and then rapidly increase with the onset of puberty, reflecting the initial recruitment of primordial follicles. AMH is produced in growing follicles until they reach a stage when dominant follicle is detached from a cohort of antral follicles. The measurement of serum AMH levels during woman's reproductive life represents an ideal tool for the assessment of the ovarian follicular reserve. The advantage of AMH in relation to the ovarian steroid hormones is that serum levels do not fluctuate significantly during the menstrual cycle. In addition, circulating AMH strongly correlates with antral follicle count (AFC), visualized by ultrasound in the follicular phase of the cycle. As the number and quality of the oocytes diminish throughout the woman's reproductive life, serum concentrations of AMH gradually decrease and fall below detectable levels in menopause. This could be of particular interest in subfertile and infertile women undergoing assisted reproductive techniques (ART) in achieving pregnancy.     

Collapsing Categorical Variables and Measurement Invariance

Cross-cultural comparisons of latent variable means demands equivalent loadings and intercepts or thresholds. Although equivalence generally emphasizes items as originally designed, researchers sometimes modify response options in categorical items. For example, substantive research interests drive decisions to reduce the number of item categories. Further, categorical multiple-group confirmatory factor analysis (MG-CFA) methods generally require that the number of indicator categories is equal across groups; however, categories with few observations in at least one group can cause challenges. In the current paper, we examine the impact of collapsing ordinal response categories in MG-CFA. An empirical analysis and a complementary simulation study suggested meaningful impacts on model fit due to collapsing categories. We also found reduced scale reliability, measured as a function of Fisher’s information. Our findings further illustrated artifactual fit improvement, pointing to the possibility of data dredging for improved model-data consistency in challenging invariance contexts with large numbers of groups.