Testosterone levels in young men in Lithuania

Abstract

The aim of study was to define testosterone reference values in young men in Lithuania. Objectives: (1) Evaluate testosterone concentration in young men and determine reference values for testosterone concentration; (2) calculate free and bioavailable testosterone using the mathematical models. Methods: Blood test results of 326 young (mean age 21 1.77 years, range 18–26 years.) male military conscripts from Lithuanian sample of international study The Reproductive Function of Estonian, Latvian and Lithuanian Young Men (QLK4-CT-1999-01422, NAS: QLK4-CT- 2001-02-11) were analysed. Concentrations of sex hormone binding globulin (SHBG) were performed by “timeresolved- immunofluorometric assay”, and total testosterone was measured by a radioimmuno-assay at the Department of Growth and Reproduction in Copenhagen. Concentrations of free and bioavailable testosterone were calculated by mathematical models. Results: Testosterone concentration varied from 3.28 to 60.8 nmol/l; the reference range for normal values as defined by mean standard deviation (SD) was 9.13– 42.52 nmol/l. Calculated free and bioavailable testosterone concentrations were 431 135 pmol/l and 7.59 2.06 nmol/l, respectively. Their respective reference normal values were 161–701 pmol/l and 3.47– 11.71 nmol/l. The reference values for optimal total, free and bioavailable testosterone in young Lithuanian men, defined as mean 1SD were 17.5–34.2 nmol/l, 296– 566 pmol/l and 5.53–9.65 nmol/l. Conclusions: Established testosterone level in a large group of young men from general population in a certain geographic region is a valuable reference for further research projects. Calculation of testosterone protein binding affinity is required to improve the accuracy of used mathematical models.