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Bioavailable Testosterone (bioavailable + testosterone)
Selected AbstractsSerum testosterone and bioavailable testosterone correlate with age and body size in hypogonadal men treated with testosterone undecanoate (1000 mg IM , Nebido®)CLINICAL ENDOCRINOLOGY, Issue 4 2008Robert Moisey Summary Objective, To investigate the loading regimen for intramuscular (IM) testosterone undecanoate (Nebido®) to determine whether testosterone and bioavailable testosterone levels achieved correlate with age or body size of subjects studied. Design, Retrospective observational study of testosterone naïve patients and patients previously treated with an alternative testosterone therapy. Patients, 51 hypogonadal men (35, 68·6% secondary hypogonadism). 8 (16%) had not previously received testosterone therapy. Measurements, Patients received an IM injection of Nebido (1000 mg) at baseline and a second injection after 6 weeks. Serum was assayed at baseline and 18 weeks after commencing Nebido for total testosterone (TT) and SHBG. Bioavailable testosterone was calculated (cBioT) using TT and SHBG. Measurements were taken for weight, body mass index (BMI) and body surface area (BSA). Results, Baseline TT (mean 11·5 nmol/l, range 0·3,54·8) increased by 50% after commencing Nebido (17·2 nmol/l (5·4,32·8), P = 0·0001). 75% of subjects had a TT within the reference range (8·0,25·0 nmol/l). Subjects with primary hypogonadism had a higher 18-week TT [20·9 nmol/l (9·8,32·8) vs. 15·5 (5·4,32·6), P = 0·02] and SHBG [39·2 nmol/l (11,82) vs. 25·7 (9·0,60·0), P = 0·003] although the cBioT was not significantly different [4·9 nmol/l (2·9,7·3) vs. 4·2 (2·0,7·9), P = 0·12]. The 18-week TT positively correlated with age (R = 0·36, P = 0·01) and negatively correlated with weight (R = ,0·38, P = 0·006), BMI (R = ,0·42, P = 0·002) and BSA (R =,0·38, P = 0·007). Similarly cBioT correlated with age (R = 0·28, P = 0·04), weight (R = ,0·29, P = 0·03), BMI (R = ,0·30, P = 0·03) and BSA (R = ,0·27, P = 0·05). Age (t = 2·04, P = 0·05) and baseline testosterone (t = ,9·26, P < 0·0001) were independent variables of the increase in TT at 18 weeks. Conclusion, This starting regimen is simple and provides the majority of men with a TT within the reference range. Age and baseline TT are independent variables of the increase in TT with IM testosterone undecanoate. At week 18 age and body size correlated with the cBioT and TT and this may then be used to estimate dosing frequency for this therapy. [source] Bone turnover markers and sex hormones in men with idiopathic osteoporosisEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 5 2001P. Pietschmann Background In contrast to osteoporosis in postmenopausal women, osteoporosis in men has received much less attention. Patients and We determined various biochemical parameters of bone metabolism and sex hormones in 31 men with idiopathic osteoporosis and 35 age matched control subjects. Results In the men with osteoporosis, a significantly increased urinary excretion of deoxypyridinoline (5·3 ± 0·2 vs. 4·6 ± 0·2 nmol mmol,1 creatinine; P = 0·033) in addition to increased serum levels of the c-terminal telopeptide of type I collagen (2677 ± 230 vs. 2058 ± 153 pmol; P = 0·037) were found. While parameters of bone formation were not significantly different in the patients and controls, serum bone sialoprotein levels were significantly decreased in the patients (3·7 ± 0·8 vs. 12·4 ± 4·0 ng mL,1; P = 0·021). Moreover, in men with idiopathic osteoporosis, lower levels of estradiol (91·3 ± 5·8 vs. 114·6 ± 7·8 pmol L,1; P = 0·044), higher levels of sex hormone binding globulin (31·5 ± 3·1 vs. 24·2 ± 1·4 nmol L,1; P = 0·034) and a decreased free androgen index (42·6 ± 5·2 vs. 56·4 ± 5·9; P = 0·016) were seen. Serum estradiol levels correlated negatively with several parameters of bone resorption. Conclusions In men with idiopathic osteoporosis, bone resorption is increased and exceeds bone formation. The excessive bone resorption seen in idiopathic male osteoporosis may be due to decreased estradiol levels and low levels of bioavailable testosterone. [source] Erectile dysfunction is associated with low bioactive testosterone levels and visceral adiposity in men with type 2 diabetesINTERNATIONAL JOURNAL OF ANDROLOGY, Issue 6 2007D. Kapoor Summary Low testosterone levels in men are associated with type 2 diabetes mellitus. Erectile dysfunction (ED) is a frequent complication of type 2 diabetes. The aim of our cross-sectional study was to investigate the relationship between ED and total, bioavailable and free testosterone levels in 198 men with type 2 diabetes. In addition, we examined the associations of various cardiovascular risk factors involved in the development of ED in type 2 diabetic men. We found that bioavailable and free testosterone levels were significantly lower in men with ED (p = 0.006 and 0.027 respectively) than those without ED. Sex hormone-binding globulin levels were also reduced, but there was no significant difference in total testosterone (TT) levels between men with and without ED. The severity of ED as assessed by International Index of Erectile Function scores was significantly associated with TT (r = 0.32; p < 0.001), bioavailable testosterone (r = 0.32; p < 0.001) and calculated free testosterone (r = 0.35; p < 0.001) levels. ED was more frequently observed in men with hypertension and a higher waist circumference (p = 0.03). There was also a higher prevalence of ED among smokers (p = 0.06), but there were no significant associations between ED and alcohol consumption or with BMI > 30. This study has shown that ED is associated with low bioavailable and free testosterone levels, age, visceral adiposity and hypertension in type 2 diabetic men. [source] Measurement-specific bioavailable testosterone using concanavalin A precipitation: Comparison of calculated and assayed bioavailable testosteroneINTERNATIONAL JOURNAL OF UROLOGY, Issue 11 2009Kenrou Yamamoto Objective: To assess the value of calculated bioavailable testosterone (cBT) and assayed BT (aBT) for the diagnosis of late-onset hypogonadism (LOH) in middle-aged and elderly subjects. Methods: In order to assay serum BT, sex hormone-binding globulin was precipitated with concanavalin-A and then testosterone was measured using liquid chromatography-tandem mass spectrometry. To validate the non-sex-hormone-binding-globulin-bound testosterone, gel filtration chromatography and concanavalin-A sepharose were used. Following this validation, the usefulness between aBT and cBT was evaluated in clinical samples. Results: Eighty-eight healthy male volunteers (mean age 65.6 years, range: 50,86) were recruited for this study. A significant correlation was found between cBT and aBT (R2 = 0.53, P < 0.01). Mean value ratio (cBT/aBT) was 2.48. Both cBT (R2 = 0.122) and aBT (R2 = 0.251) decreased with age. Variations in aBT were less marked than those for cBT, suggesting that aBT can be used to determine age-related reduced testosterone levels. Conclusion: aBT levels are more reliable than cBT levels for the diagnosis of LOH in middle-aged and elderly subjects. [source] ORIGINAL RESEARCH,ENDOCRINOLOGY: Evaluation of the Effects of Cigarette Smoking on Testosterone Levels in Adult MenTHE JOURNAL OF SEXUAL MEDICINE, Issue 6 2009Graziele Halmenschlager MS ABSTRACT Introduction., Cigarette smoking is highly prevalent among men. Many studies have evaluated the effect of cigarette smoking on levels of male reproductive hormones; however, the findings still remain controversial. Aim., To evaluate the influence of cigarette smoking on serum levels of total testosterone (TT), free testosterone (FT), bioavailable testosterone (BT), sex hormone-binding globulin (SHBG), luteinizing hormone (LH), and follicle-stimulating hormone (FSH). Methods., A total of 255 men (90 smokers and 165 nonsmokers), aged 30 to 70 years, were investigated. Weight and height were obtained and body mass index (BMI) was calculated. Also, waist circumference and hip circumference were measured and waist-to-hip ratio was obtained. Fasting blood samples were drawn for determination of plasmatic glucose levels and serum levels of total cholesterol, high-density lipoprotein cholesterol (HDL-c), triglycerides, albumin, prolactin, TT, SHBG, LH, and FSH. The values of low-density lipoprotein cholesterol (LDL-c) were determined by Friedwald equation and the values of FT and BT were calculated from TT, SHBG, and albumin. Statistical significance was set at P , 0.05. Main Outcome Measures., The influence of smoking on levels of TT, FT, and BT. Results., No significant difference was observed in the mean values of TT (P = 0.580), FT (P = 0.869), BT (P = 0.933), SHBG (P = 0.279), LH (P = 0.573), and FSH (P = 0.693) in the different levels of pack-years when compared to nonsmokers. Moreover, after multivariate logistic regression, no association between increased pack-years of smoking and increased odds ratio for occurrence of low hormones and SHBG levels was observed. Conclusion., In this study, smokers and nonsmokers had similar mean values of androgens, gonadotropins and SHBG. However, it is necessary to standardize pack-years of smoking in order to elucidate the influence of cigarette smoking on sex hormone levels, as well as to minimize differences among studies and to confirm our results. Halmenschlager G, Rossetto S, Lara GM, and Rhoden EL. Evaluation of the effects of cigarette smoking on testosterone levels in adult men. J Sex Med 2009;6:1763,1772. [source] Serum sex hormones and the 20-year risk of lower urinary tract symptoms in community-dwelling older menBJU INTERNATIONAL, Issue 11 2010Michael D. Trifiro Study Type , Prognosis (inception cohort) Level of Evidence 2b OBJECTIVE To evaluate serum sex steroid hormone concentrations and long-term risk of subsequent lower urinary tract symptoms (LUTS) in a cohort of community-dwelling older men. SUBJECTS AND METHODS Between 1984 and 1987, serum sex hormone concentrations were measured in participants in the Rancho Bernardo Study, a prospective, community-based study. In 2006, the American Urological Association Symptom Index (AUA-SI) was mailed to surviving male participants. Logistic regression was used to examine associations of baseline hormone concentrations with AUA-SI. RESULTS Among 158 surviving men with complete data and no history of prostate cancer, the mean (sd) age at serum sex steroid assessment was 58 (6.6) years with a mean (sd) follow-up of 20.3 (0.6) years. In age-adjusted logistic regression, there was a significant inverse association of testosterone : dihydrotestosterone (DHT) with LUTS (P = 0.05). Also, men with higher concentrations of bioavailable testosterone had a 56% decreased risk of LUTS compared with those with hypogonadal concentrations, although the association was not statistically significant (odds ratios 0.44, 95% confidence interval 0.14,1.40) or distributed evenly among quartiles. There were no significant associations of total testosterone, oestradiol (E2), testosterone : E2, DHT, or dehydroepiandrosterone with LUTS or with any measured hormones and urinary bother. CONCLUSIONS In this cohort, men with higher mid-life levels of testosterone : DHT and bioavailable testosterone had a decreased 20-year risk of LUTS. These data support other studies reporting inverse associations of serum testosterone with LUTS. Clinical trials of testosterone therapy should include LUTS and clinical benign prostatic hyperplasia as outcomes. [source] Diurnal rhythms of serum total, free and bioavailable testosterone and of SHBG in middle-aged men compared with those in young menCLINICAL ENDOCRINOLOGY, Issue 6 2003Michael 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. 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