Plasma Free Testosterone—is An Index Sufficient?

Nanjee, M. Nazeem; Wheeler, Michael J.

doi:10.1177/000456328502200410

Cited by 116 publications

(74 citation statements)

References 6 publications

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“…It does not take into account testosterone bound to albumin or cortisol-binding protein (22). This method has been found to give free testosterone results that correlate closely with those directly measured by using the antibody-coated tube radioimmunoassay method (23)(24)(25).…”

Section: Hormone Assaysmentioning

confidence: 90%

Sexual Function in Women with Epilepsy

et al. 1997

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Summary:Purpose: To examine certain aspects of sexual behaviour and attitudes in a group of women with epilepsy using a validated questionnaire (Sexuality Experience Scales), and effects of antiepileptic drugs (AEDs) on sex hormone binding globulin (SHBG), total testosterone (TT), and free testosterone (FT).Methods: One hundred ninety-five women all attending a hospital-based epilepsy clinic were recruited. One hundred fifty-nine received AED therapy and 36 women did not. A control group of 48 women was also recruited. All women completed the first two Sexuality Experience Scales (SES 1 and SES 2), and those women in stable heterosexual relationships completed SES 3 and SES 4. At the same time blood was taken for TT and SHBG 1evels.FT was calculated using the method of Nanjee and Wheeler (22).Results: Women receiving AED therapy achieved significantly higher SES 1 and SES 2 scores than the rest of the women, suggesting that they adhered to a stricter sexual morality and were less open to psychosexual stimulation than the rest of the women treated. Women in the treated group were less likely to have received further education than the controls, a factor that influences SES 1 and SES 2 scores. There were no significant differences between the three groups on SES 3 or SES 4, with the exception of the orgasmic adequacy (OE) scale of SES 3 where those women in the treated group attained a higher mean score than the controls, suggesting that they found orgasm less satisfying. Women receiving AEDs had significantly higher SHBG and TT than controls and untreated patients. There were no differences in FT between the groups. Those women receiving AEDs also exhibited the expected midcycle rise in FT. There was no significant correlation between FT and the desired frequency of intercourse or enjoyment of it for the three groups.Conclusions: Women in the treated group appeared to be more "moral" and less open to sexual approach, but those who had regular partners appeared to desire and enjoy intercourse as much as the control and untreated groups. This could be explained by differences in demographic characteristics of the study groups or be indicative of a bimodal distribution of sexual interest in these women. As FT was within physiological norms for each study group this cannot be cited as a cause for hyposexuality .

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Section: Hormone Assaysmentioning

confidence: 90%

Sexual Function in Women with Epilepsy

et al. 1997

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“…Only these latter two fractions are available to tissues and are thus termed BT. Free testosterone can be calculated 35,36 or measured by equilibrium dialysis. One measure of FT is the free androgen index (FAI ¼ TT/SHBG Â 100).…”

Section: Controversies In Diagnosismentioning

confidence: 99%

Male hypogonadism. Part I: Epidemiology of hypogonadism

Seftel

2005

Int J Impot Res

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Male hypogonadism is a frequent and potentially undertreated condition. A number of longitudinal epidemiologic studies, including the Baltimore Longitudinal Study of Aging, the New Mexico Aging Process Study, and the Massachusetts Male Aging Study, have demonstrated age-related increases in the likelihood of developing hypogonadism. In addition to advancing age, increasing body mass index and/or type II diabetes mellitus may be associated with lower circulating androgen levels. Owing to the demographic trends toward increasing population age and life expectancy, together with the emerging pandemic of diabetes and recent trend toward an increasing prevalence of obesity in the United States, clinicians are likely to encounter increasing cases of hypogonadism in the near future.

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“…Intra-and interassay CVs were 7.7% and 7.1% (at SHBG 24.1 nmol/l) and 4.2% (at SHBG 103 nmol/l). An index of 'free', biologically active testosterone, the free androgen index (FAI), was derived from the ratio total testosterone/ SHBG×100 (24). Urinary pyridinolines, and serum osteocalcin and collagen type I C-terminal propeptides (CICP), markers of bone turnover, were measured by RIA and IRMA as we have validated and reported previously (25).…”

Section: Laboratory Measurementsmentioning

confidence: 99%

Relationship of chronic endurance exercise to the somatotropic and sex hormone status of older men

Cooper

Taaffe

Guido

et al. 1998

European Journal of Endocrinology

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To investigate putative abrogating effects of habitual endurance exercise on age-related changes in endocrine function and body composition, we compared insulin-like growth factor-I (IGF-I), sex hormonal status and body composition in 15 Masters runners and 15 minimally exercising men (MEM) aged 60-70 years. A higher maximal oxygen uptake (VO 2 max.) in the runners (41.4 Ϯ 1.6 compared with 27.3 Ϯ 1.4 ml/kg/min, P ¼ 0.0001; mean Ϯ S.E.M.) reflected our group allocations. Analysis of body composition and bone mineral density (BMD) by dual energy X-ray absorptiometry showed no group differences in lean tissue mass or in regional or whole body BMD, but MEM were heavier, reflecting greater adiposity. Of nine muscle groups tested, only quadriceps strength differed significantly, being greater in runners (60.3 Ϯ 2.8 compared with 51.1 Ϯ 2.3 kg, P ¼ 0.02). Total IGF-I (129 Ϯ 10 compared with 124 Ϯ 11 ng/ml, P ¼ 0.72) and IGF-binding protein-3 (2854 Ϯ 94 compared with 2623 Ϯ 128 ng/ml, P ¼ 0.16), were similarly depressed compared with young adult norms in both groups. There was no relationship between total or bioavailable IGF-I and any body composition, BMD or muscle strength variable. In the runners, concentrations of total testosterone (19.1 Ϯ 0.8 compared with 15.0 Ϯ 0.9 nmol/l, P ¼ 0.002) and sex hormone binding globulin (SHBG) (124.4 Ϯ 21.6 compared with 67.7 Ϯ 11.6 nmol/l, P ¼ 0.03) were significantly greater, but the free androgen index was significantly lower (20.7 Ϯ 2.7 compared with 31.4 Ϯ 4.1, P ¼ 0.04). Directly measured free testosterone, however, was similar between the runners and MEM (47.9 Ϯ 1.8 compared with 47.1 Ϯ 2.0 nmol/l, P ¼ 0.80). Therefore the group differences in total testosterone and free androgen index were due to their different SHBG concentrations. Although estrone concentration was higher in MEM (85.1 Ϯ 5.2 compared with 108 Ϯ 6.7 pmol/l, P ¼ 0.03), estradiol concentration was similar between groups (73.0 Ϯ 6.3 compared with 81.8 Ϯ 8.0 pmol/l, P ¼ 0.18), indicating that estrogens were not responsible for the increased SHBG in runners. These results indicate that even high levels of regular endurance exercise do not prevent the decline in the somatotropic axis that occurs with aging. Furthermore, the somatic effects of exercise in older men (reduced adiposity and increased regional muscle strength) occurred independently of somatotropic or androgen status. Although habitual exercise does not influence free testosterone concentrations in older men, it appears to enhance the age-associated increase in SHBG synthesis.

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Plasma Free Testosterone—is An Index Sufficient?

Cited by 116 publications

References 6 publications

Sexual Function in Women with Epilepsy

Sexual Function in Women with Epilepsy

Male hypogonadism. Part I: Epidemiology of hypogonadism

Relationship of chronic endurance exercise to the somatotropic and sex hormone status of older men

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