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Serum Total Testosterone (serum + total_testosterone)

Distribution by Scientific Domains

Medical Sciences	50%

Selected Abstracts

Long-term effects of calorie restriction on serum sex-hormone concentrations in men

AGING CELL, Issue 2 2010
Roberto Cangemi
Summary Calorie restriction (CR) slows aging and consistently reduces circulating sex hormones in laboratory animals. However, nothing is known regarding the long-term effects of CR with adequate nutrition on serum sex-hormone concentration in lean healthy humans. In this study, we measured body composition, and serum total testosterone, total 17-,-estradiol, sex hormone,binding globulin (SHBG), and dehydroepiandrosterone sulfate (DHEA-S) concentrations in 24 men (mean age 51.5 ± 13 years), who had been practicing CR with adequate nutrition for an average of 7.4 ± 4.5 years, in 24 age- and body fat,matched endurance runners (EX), and 24 age-matched sedentary controls eating Western diets (WD). We found that both the CR and EX volunteers had significantly lower body fat than the WD volunteers (total body fat, 8.7 ± 4.2%; 10.5 ± 4.4%; 23.2 ± 6.1%, respectively; P = 0.0001). Serum total testosterone and the free androgen index were significantly lower, and SHBG was higher in the CR group than in the EX and WD groups (P , 0.001). Serum 17,-estradiol and the estradiol:SHBG ratio were both significantly lower in the CR and EX groups than in the WD group (P , 0.005). Serum DHEA-S concentrations were not different between the three groups. These findings demonstrate that, as in long-lived CR rodents, long-term severe CR reduces serum total and free testosterone and increases SHBG concentrations in humans, independently of adiposity. More studies are needed to understand the role of this CR-mediated reduction in sex hormones in modulating the pathogenesis of age-associated chronic diseases such as cancer and the aging process itself. [source]

Cigarette smoking is related to a decrease in semen volume in a population of fertile men

BJU INTERNATIONAL, Issue 2 2006
FÁBIO F. PASQUALOTTO
OBJECTIVE To evaluate the semen quality and hormonal levels in fertile men according to their level of cigarette smoking. SUBJECTS AND METHODS We evaluated 889 fertile men who came for a vasectomy for sterilization purposes. The men included 522 non-smokers, 143 mild smokers (<10 cigarettes/day), 154 moderate smokers (11,20/day), and 70 heavy smokers (>20/day). We evaluated sperm concentration, motility, motion variables and hormonal levels in these men. RESULTS There were no significant differences among the groups in sperm concentration or motility, or in levels of follicle-stimulating hormone, luteinizing hormone, or serum total testosterone. Also, sperm motion characteristics did not differ across the groups. Semen volume was the only semen variable which tended to decrease according to the number of cigarettes smoked. CONCLUSIONS Cigarette smoking had no apparent effect on sperm concentration, motility or reproductive hormonal levels, but tended to reduce semen volume. [source]

Diurnal rhythms of serum total, free and bioavailable testosterone and of SHBG in middle-aged men compared with those in young men

CLINICAL ENDOCRINOLOGY, Issue 6 2003
Michael J. Diver
Summary background Conflicting views are reported on the association between advancing age and gradually diminishing concentrations of serum total testosterone in men. The putative loss of diurnal rhythm in serum total testosterone in older men is reported to be in part due to low concentrations in the morning when compared to concentrations found in young men. We have measured total, free and bioavailable testosterone along with SHBG in samples taken every 30 min throughout a 24-h period in 10 young and eight middle-aged men. results Both young and middle-aged men displayed a significant diurnal rhythm in all variables, with a minimum fall of 43% in total testosterone from peak to nadir in all subjects. Subjecting the data to a time series analysis by least squares estimation revealed no significant difference in mesor (P = 0·306), amplitude (P = 0·061) or acrophase (P = 0·972) for total testosterone between the two groups. Comparing bioavailable testosterone in the two groups revealed no significant difference in mesor (P = 0·175) or acrophase (P = 0·978) but a significant difference (P = 0·031) in amplitude. Both groups display a significant circadian rhythm (middle-aged group P < 0·001; young group P = 0·014). Free testosterone revealed a highly significant rhythm in both the young group (P < 0·001) and the middle-aged group (P = 0·002), with no significant difference between the groups in mesor (P = 0·094) or acrophase (P = 0·698). Although analysis of the SHBG data revealed a significant rhythm in the young group (P = 0·003) and the older group (P < 0·001), the acrophase occurred in the mid afternoon in both groups (15·12 h in the young and 15·40 h in the middle-aged). The older men had a significantly greater amplitude (P = 0·044) but again no significant difference was seen in mesor (P = 0·083) or acrophase (P = 0·477) between the two groups. Acrophases for total, bioavailable and free testosterone occurred between 07·00 h and 07·30 h; for SHBG the acrophase occurred at 15·12 h in the young group and 15·40 h in the middle-aged group. conclusions The study suggests that the diurnal rhythm in these indices of androgen status is maintained in fit, healthy men into the 7th decade of life. [source]