Biological variation of plasma 25-Hydroxyvitamin D3, Serum vitamin B12, folate and ferritin in Turkish healthy subject.

Biological variation (BV) plays a crucial role in determining analytical performance specifications, assessing serial measurements of individuals, and establishing the use of population-based reference intervals. Our study aimed to calculate the BV and BV-based quality goals of 25-hydroxyvitamin D3 (25-OH D3), ferritin, folate and vitamin B12 tests. We included a total of 22 apparently healthy volunteers (9 women and 13 men) aged 18-55 years in the study that we conducted in Turkey. Blood samples were collected from the participants once a week for five weeks. Serum ferritin, folate and vitamin B12 levels were measured using immunochemical method, while plasma 25-OH D3 levels were determined using the high-performance liquid chromatography method. Analysis of variance (ANOVA) was used to estimate analytical variation(CVA), within-subject BV(CVI) and between-subject BV(CVG). The individuality index (II) and reference change value (RCV) were calculated based on these data. The CVI of 25-OH D3, ferritin, folate, and vitamin B12 were found to be 1.8% (0.6%-2.5%), 16.9% (14.4%-20.2%), 10.7% (9.2%-12.7%), and 8.6% (6.8%-10.5%), respectively. CVG were 44.2% (34.3%-69.9%), 132% (87.7%-238%), 19.4% (14.4%-28.8%), and 39.6% (29.8%-59.0%) for the same biomarkers, while CVA were 3.2% (2.81%-3.71%), 3.5% (3.1%-4.1%), 4.0% (3.5%-4.6%), and 7.5% (6.6%-8.6%), respectively. The II values for 25-OH D3, ferritin, folate, and vitamin B12 were calculated as 0.04, 0.13, 0.55, and 0.22, respectively. The RCV were 10.2%, 47.8%, 31.7%, and 31.6%, respectively. Because the tests analyzed in this study exhibit high individuality, RCV should be preferred rather than population-based reference ranges in clinical interpretation of results.

Monitoring the response to treatment of acute heart failure patients by ultrasonographic inferior vena cava collapsibility index.

OBJECTIVE: Our aim was to determine if N-terminal pro-brain natriuretic peptide (NT-proBNP) or sonographic measurements of inferior vena caval (IVC) diameters and collapsibility index (IVC-CI) have a role in the monitoring of acute heart failure (AHF) therapy. METHODS: Inferior vena caval diameters of 50 healthy people (control group) were measured to determine the normal values of the IVC parameters. We then prospectively enrolled patients who were admitted to the emergency department (ED) with a primary diagnosis of AHF. At presentation, IVC diameters were measured during expiration and inspiration, and blood was drawn for NT-proBNP. We repeated the measurement of the IVC parameters and collected a second blood sample 12 hours after the therapy was administered. The data were analyzed in SPSS 15.0 (IBM, Armonk, NY) using the Student t test and Mann-Whitney U test. RESULTS: A total of 97 subjects were enrolled: 47 in the patient group and 50 in the control group. The mean IVC during expiration was 2.10 ± 0.37 cm before and 1.57 ± 0.24 cm after the therapy (P < .001). The mean IVC during inspiration was 1.63 ± 0.40 cm before and 0.90 ± 0.26 cm after the therapy (P < .001). The mean IVC-CI rose from 22.80% ± 10.97% to 43.09% ± 13.63% (P < .001). After the therapy, there was no difference between the IVC-CI of the patients and controls (P = .246). There was no significant change in the mean NT-proBNP levels after the therapy. CONCLUSION: Inferior vena caval collapsibility index may be helpful in monitoring AHF patients' responses to therapy in the ED.