Clinical evaluation of a new non-isotopic leptin immunoassay.

OBJECTIVE

Evaluate the new Active human leptin ELISA available through Diagnostic Systems Laboratories Inc for use in clinical research laboratories.

DESIGN

Fasting plasma samples for this study were obtained randomly from human subjects. Precision, linearity, recovery, and interference studies were performed, in addition to method comparison with the conventional leptin RIA method and comparison between laboratories.

SETTING

University of Hawaii at Manoa, Division of Medical Technology and the Native Hawaiian Health Research-RCMI laboratory.

PARTICIPANTS

Native Hawaiians were selected for this study since this population has consistently demonstrated a higher incidence rate of obesity and Type 2 diabetes and thus, potentially have high leptin levels.

RESULTS

At leptin concentrations of 2.3, 16.6, and 45.6 ng/ mL, within-run imprecision (n = 5) ranged from 3.1%, 1.6%, and 4.2%, and the between-run imprecision (n = 10) ranged from 6.8%, 4.1%, and 2.7%. The comparison-of-method gave a linear regression equation of y = 0.92x + 1.6 mg/dL (r = 0.96, n = 74, S(y/x) 2.0) when compared to the Linco human leptin RIA method. The dilution curve showed acceptable linearity within the reportable range of the assay, and the recovery was 88.5% to 112%. No interference was detected with hemoglobin up to 1 g/dL, and with triglyceride, up to 1.8 g/dL. However, bilirubin, 10 mg/dL, did show significant interference.

CONCLUSION

Overall, we feel that the new Active Human Leptin assay offers a safe and rapid alternative method appropriate for clinical research laboratories and epidemiological studies.