The reliability of single time point measurements of the novel adipokines
retinol-binding protein 4 and omentin-1 in the blood has not been evaluated in
large samples yet. The present study aimed to assess the amount of biological
variation of these two adipokines within individuals. The study sample
comprised 207 participants (124 women and 83 men) from Potsdam (Germany) and
surrounding areas, with an average age of 56.5 years (SD 4.2). Blood samples
were collected from each participant twice, approximately four months apart.
Using enzyme linked immunosorbent assays, the concentrations of retinol-
binding protein 4 and omentin-1 were determined in EDTA plasma. As indicators
of reliability, intraclass correlation coefficients (ICCs) were calculated
from the repeated biomarker measurements. The ICCs for repeated retinol-
binding protein 4 and omentin-1 measurements were 0.77 (95% CI 0.71, 0.82) and
0.83 (95% CI 0.78, 0.87), respectively, indicating for both adipokines
excellent reliability. ICCs were stable across strata according to sex, age,
BMI, and blood pressure. Thus, for epidemiological studies it seems reasonable
to rely on concentrations of retinol-binding protein 4 and omentin-1 in
samples from a single time point if repeated measurements are not available
