The Association Of Time Of Day And Serum Testosterone Concentration In A Large Screening Population

Main Category: Prostate / Prostate Cancer
Also Included In: Urology / Nephrology;  Men's health
Article Date: 15 Jul 2007 - 0:00 PDT


UroToday.com- Testosterone levels in older men are stable throughout the day and decline 13% in the later afternoon according to a report by Dr. Davis Crawford and associates that appears in the online version of the BJU International.

The researchers evaluated 3,006 men participating in Prostate Cancer Awareness Week Screening. They sought to investigate the distribution of the diurnal variation of testosterone over the course of the day and to examine the impact of age, obesity, race, and comorbidities on the testosterone levels. Men completed a questionnaire and testosterone levels were measured at one central laboratory. Four groups were stratified based upon time of day the blood was drawn; T1, 6:00-10:00 (632 men), T2, 10:00-12:00 (812 men), T3, 12:00-14:00 (388 men), and T4, 14:00-18:00 (1,174 men).

The population had 18% of men characterized as obese and 8% had diabetes. There were no diurnal changes in the median PSA levels among the four time groups. Mean testosterone levels were lower in diabetics than non-diabetics and or obese men compared to non-obese. Thirty-one percent of men had testosterone levels <300ng/dL and 14% had levels <231ng/dL (the threshold for hypogonadism). Testosterone levels did not differ between the first three time groups (T1-T3) but all 3 groups were higher than group T4 by 13%. Men in T4 were slightly older (61 years) than men in T1-3 (60 years). The significantly lower level in the late group was for all ages studied.

Crawford ED, Barqawi AB, O'Donnell C and Morgentaler A

BJU Int. ePub: June 6, 2007
doi:10.1111/j.1464-410X.2007.07022.x

Reported by UroToday.com Contributing Editor Christopher P. Evans, M.D

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