Reference intervals for important serum sex steroid hormones, prostate-specific antigen, insulin-like growth factor-1 and IGF binding protein-3 concentration in a normal Kuwaiti adult male population.

OBJECTIVES The purpose of this study was to determine the age-specific reference ranges for some important male sex steroid hormones, prostate-specific antigen (PSA), insulin-like growth factor-1 (IGF-1), and IGF binding protein-3 (IGFBP-3), for the Kuwaiti population. SUBJECTS AND METHODS Blood samples were taken from 398 consenting, fasting, healthy Kuwaiti males aged 15-80 years between 8.00 a.m. and 12.00 noon. The serum concentrations of total testosterone (TT), dehydro-epiandrosterone sulfate (DHEAS), androstenedione (ADT), sex hormone binding globulin, luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin, PSA, IGF-1 and IGFBP-3 were determined. A distribution curve was plotted and age-specific reference levels were determined for each analyte. The reference interval for parameters with a normal distribution (Gaussian) was mean +/- 2 SD, while for the non-normal distribution (non-Gaussian), it was 2.5-97.5 percentile. The reference intervals for the analytes obtained from this study were compared with those suggested by the kit manufacturers and currently used by the Ministry of Health, Kuwait Laboratories (MOHKL). RESULTS Serum IGFBP-3 and ADT had normal distribution while other analytes had non-normal distribution. The reference intervals from this study, manufacturers kit and MOHKL were as follows: TT 3-31, 9-60, 8-35 nmol/l; DHEAS 0.9-11, 1.0-7.3, 2.2- 15.2 micromol/l; ADT 0.5-4.3, 0.8-2.8, 2.0-9.2 nmol/l; LH 1-11, 0.8-7.6, 0.4-5.7 mIU/l; FSH 0.5-11, 0.7-11.1, 1.1-13.5 mIU/l; prolactin 42-397, 53-360, 80-230 nmol/l; IGF-1 41-542, 78-956, 71-261 ng/ml; IGFBP-3 88- 2,090, 900-4,000, 900-4,000 ng/ml, and PSA 0-3.1, 0-4, 0-4 ng/ml, respectively. CONCLUSION These data indicate that for Kuwaitis lower reference ranges must be used for serum TT, DHEAS, ADT, IGFBP-3 and PSA. There is no need to change the currently used reference interval for FSH whereas higher values must be used for LH, prolactin, and IGF-1.