Biological variation of peripheral blood T-lymphocytes.

BACKGROUND: Flow cytometric analysis of the lymphocyte subsets has become one of the most commonly used techniques in the routine clinical laboratory. It is frequently used in monitoring lymphocyte recovery after hematopoietic stem cell transplantation (HSCT), as well as diagnosis and treatment of acquired immunodeficiency syndrome (AIDS). Reliable biological variation (BV) data is needed for safe clinical application of these tests. In this study, similar preanalytical and analytical protocols to the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) checklist were followed and a stringent statistical approach was applied to define BV of T-lymphocytes. METHODS: During the 10 weeks study period, weekly blood samples were obtained from 30 healthy individuals (20 females, 10 males) and analyzed with Facs Canto (BD Biosciences, San Jose, CA, USA) analyzer using 4-colour BD Multitest CD3/CD8/CD45/CD4 reagents. Data were assessed in terms of normality, tendencies, outliers and variance homogeneity prior to applying coefficient of variance (CV)- analysis of variance (ANOVA) test. Sex-stratified within-individual (CVI) and between-individual (CVG) BV estimates of CD3+, CD3 + CD4+, CD3 + CD8+, and CD3 + CD4 + CD8+ T lymphocytes were calculated. RESULTS: No difference was found between males and females. Except for the CD3 + CD4 + CD8+ subset, stable BV was found for CD3+, CD3 + CD4+, and CD3 + CD8+ subsets. CONCLUSSION: Instead of using the conventional reference ranges of CD3+, CD3 + CD4+ and CD3 + CD8+ counts for monitoring HIV positive or post-HSCT patients, RCV should be used. Because individualityis characteristic of lymphocytes subsets RCVs should be used instead of RIs for patient monitoring.

Biological variation estimates of prothrombin time, activated partial thromboplastin time, and fibrinogen in 28 healthy individuals.

BACKGROUND: Although tests of global hemostasis prothrombin time (PT) and activated partial thromboplastin time (aPTT) should not be used for prediction of bleeding risk, these tests are often used by many clinicians in daily practice particularly as a preoperative screening test. Robust biological variation (BV) data are needed for safe clinical applications of these tests. In this study, a stringent protocol was followed to estimate the BV's for PT, aPTT, and fibrinogen levels. METHODS: Weekly blood samples were obtained from 28 healthy individuals (18 females, 10 males) during 10 weeks study period. All measurements were performed with Stago STA-R coagulation analyzer. Prior to coefficient of variation (CV)-analysis of variance (ANOVA), the data were assessed for normality, trends, outliers, and variance homogeneity. Sex-stratified within-individual (CVI ) and between-individual (CVG ) BV estimates were determined for PT, aPTT, and fibrinogen tests. RESULTS: No difference was found between male and female estimates of BV. The observed CVI and CVG estimates were found to be lower than those previously published. Only for fibrinogen, CVI was higher than CVG . CONCLUSION: Following a meticulous protocol, our study results provide up-to-date and more stringent BV estimates of global hemostasis tests.