Evaluation of plasma hormone concentrations using Enzyme-Immunoassay/Enzyme-linked Immunosorbent assay in healthy Indian men: Effect of ethnicity.

The study involved three ethnic groups of India; Rajputs, Gorkhas and South-Indians. Each group consisted of ∼40 healthy, male soldiers between 20-50 years. The reference ranges for cortisol, testosterone, prolactin, arginine vasopressin and proAtrial natriuretic peptide(1-98) were determined using Enzyme-Immunoassay (EIA) while plasma levels of thyroid-stimulating hormone, triiodothyronine, free-triiodothyronine, thyroxine and freethyroxine were measured using Enzyme-linked immunosorbent assay (ELISA). The results indicated that plasma hormone concentrations were within physiological range and inter-ethnic differences were most prominent between north- (Rajputs and Gorkhas) and south- Indians. In comparison to Radioimmunoassay, the EIA method for prolactin, thyroid-stimulating hormone, free-thyroxine gave higher values while the ELISA method for triiodothyronine, free-triiodothyronine, and thyroxine gave lower values. These differences are due to differences in assay standards and design.