MEASURING MALE REPRODUCTIVE HORMONES FOR OCCUPATIONAL FIELD STUDIES

As part Of our longitudinal study of unexposed workers, we drew blood samples and analyzed the individual endocrine profiles for 45 men. The blood collection was between 8 Am and 8 PM, and three blood samples w ere drawn 20 minutes apart on three occasions during the course of the study (June, October, and February). Serum concentrations of follicle -stimulating hormone, luteinizing hormone, testosterone, and prolactin were determined. A component of variance model was used to estimate v ariability between the 20-minute blood draws. Statistical power analys is using this component showed that three blood draws provide a margin al improvement over a single blood draw in detecting population shifts . Also, if the prospect of three blood draws reduces subject participa tion by 10 to 20%, the increase in power would be negated.