Defining 'relative' androgen deficiency in aging men: how should testosterone be measured and what are the relationships between androgen levels and physical, sexual and emotional health?

Low testosterone at age 31 associates with maternal obesity and higher body mass index from childhood until age 46: A birth cohort study

BACKGROUND

Low testosterone (T) levels in men associate with increased risks of obesity, type 2 diabetes, metabolic syndrome, and cardiovascular diseases. However, most studies are cross-sectional with follow-up-time < 10 years, and data on early growth are limited.

OBJECTIVE

To compare prenatal factors and body mass index (BMI) development from birth to age 46 in relation to low T at age 31.

MATERIALS AND METHODS

Men with low T (T < 12.1 nmol/L, n = 132) and men with normal T at age 31 (n = 2561) were derived from the Northern Finland Birth Cohort 1966. Prenatal factors, longitudinal weight and height data from birth to age 14, and cross-sectional weight and height data at ages 31 and 46, and waist-hip-ratio (WHR) and T levels at age 31 were analyzed. Longitudinal modeling and timing of adiposity rebound (AR, second BMI rise at age 5-7 years) were calculated from fitted BMI curves. Results were adjusted for mother's pre-pregnancy BMI and smoking status, birth weight for gestational age, alcohol consumption, education level, smoking status, and WHR at age 31.

RESULTS

Neither gestational age nor birth weight was associated with low T at age 31; however, maternal obesity during gestation was more prevalent among men with low T (9.8% vs. 3.5%, adjusted aOR: 2.43 [1.19-4.98]). Men with low T had earlier AR (5.28 vs. 5.82, aOR: 0.73 [0.56-0.94]) and higher BMI (p < 0.001) from AR onward until age 46. Men with both early AR and low T had the highest BMI from AR onward.

CONCLUSIONS

In men, maternal obesity and early weight gain associate with lower T levels at age 31, independently of adulthood abdominal obesity. Given the well-known health risks related to obesity, and the rising prevalence of maternal obesity, the results of the present study emphasize the importance of preventing obesity that may also affect the later reproductive health of the offspring.

Dose-dependent effects of Asparagus adscendens root (AARR) extract on the anabolic, reproductive, and sexual behavioral activity in rats

CONTEXT

Asparagus adscendens Roxb (Liliaceae) has a promising role in modulation of various disorders such as leucorrhea, diarrhea, dysentery, diabetes, senile pruritus, asthma, fatigue antifilarial, antifungal, spermatorrhea, and sexual debility/seminal weakness.

OBJECTIVE

To investigate dose-dependent effects of Asparagus adscendens root (AARR) extract on anabolic, reproductive, and sexual behavioral activities with a view to emphasize the pharmacological basis.

MATERIALS AND METHODS

Rats were divided into five groups: Group I (control), Groups II-IV (AARR treated, 100, 200, and 300 mg/kg body weight, respectively, orally for 30 d) and Group V (standard control treated with sildenafil citrate, 5 mg/kg body weight). On day 31, copulatory and potency tests were carried out and an autopsy was done to study the reproductive function, namely, organ weights, spermatogenesis, daily sperm production rate (DSP), and epididymal sperm counts (ESC).

RESULTS

AARR extract (200 and 300 mg/kg doses) caused a significant increase in body (p < 0.02 and p < 0.001) and testes (p < 0.01 and p < 0.001, control versus treated) weights. Reproductive activity showed significant a increase in testicular tubular diameter (p < 0.005-0.001), the number of round/elongated spermatids (p < 0.02-0.001), DSP, and ESC (p < 0.05-0.001). The sexual behavioral parameters including mounting/intromission frequency (13.0 ± 0.32/11.8 ± 0.37 and 18.2 ± 2.12/14.8 ± 1.15 versus 11.2 ± 0.66/8.2 ± 1.16), ejaculation latency (187.4 ± 1.91 and 191.4 ± 1.72 versus 180.0 ± 3.47), and penile erections (13.5 ± 0.3 and 14.5 ± 0.5 versus 8.5 ± 0.2) showed a significant increase at 200 and 300 mg/kg doses (ED50 300 mg/kg), but less than a standard control. In contrast, 100 mg/kg dose caused an increase (p < 0.005) in mounting latency only.

CONCLUSION

These results indicate increased anabolic, reproductive, and sexual activities by AARR treatment. Thus, the data provide scientific rationale for its traditional use as an aphrodisiac or for sexual disorders.

Mondia whitei, a medicinal plant from Africa with aphrodisiac and antidepressant properties: a review

This paper reviews the literature concerning the ethnobotany, phytochemistry, and pharmacology of Mondia whitei, which is also known as Mondia whytei, African ginger or simply as mondia. Mondia is used in many parts of Africa as a traditional remedy to improve appetite and libido, as a galactagogue, as a fertility medication, and as an antidepressant. In African countries, where it is used medicinally, the most commonly cited use is as an aphrodisiac. The scientific studies reviewed in this report employed either in vivo rodent models or isolated organ techniques, and therefore the results cannot be directly extrapolated to humans. Nevertheless, these studies provide scientific evidence that support the traditional uses of mondia as an aphrodisiac and an antidepressant. Based on the safety data available in the literature, mondia is reasonably expected to be safe when prepared and used according to traditional practices.

Serum testosterone bioassay evaluation in a large male cohort

OBJECTIVE

To assess if a cell-based readout of androgen action in serum demonstrates a closer association with recognized classical parameters of androgen action in men than current measures of serum testosterone (T).

DESIGN

To develop, validate and utilize a mammalian cell-based assay to measure specifically bioactive T and determine if this measure is a physiologically relevant fraction of serum T. MEASUREMENTS AND PARTICIPANTS: We have developed a specific serum T bioassay using human prostate cancer cells. A rapid 5-min exposure to 100% serum followed by serum withdrawal confers specificity of the assay to serum T and provides sufficient sensitivity to measure T in male serum samples. Matrix effects were experimentally discounted as a confounding issue. A total of 960 male serum samples from the Florey Adelaide Male Ageing Study (FAMAS) with previous comprehensive cohort data and serum measurements were utilized.

RESULTS

Bioassay T measurement in the 960 FAMAS serum samples returned a median of 10.7 nmol/l (1.7-45.4), and was most closely related to immunoassayed total T, but not immunoassayed bioavailable T or calculated free T. Immunoassayed total T demonstrated a positive association with isometric grip-strength (R(2) = 0.127, P < 0.001), self-reported sexual desire (R(2) = 0.113, P < 0.001) and erectile function (R(2) = 0.085, P < 0.05) while bioassay T did not.

CONCLUSIONS

While cellular bioassays offer a rapid and sensitive means of identifying the androgenic potential of complex environmental compounds, the utility of such assays in defining a clinically relevant fraction of serum T distinct from total T needs further investigation.

A comparative study on aphrodisiac activity of some ayurvedic herbs in male albino rats

The roots of Asparagus racemosus, Chlorophytum borivilianum, and rhizomes of Curculigo orchioides are popular for their aphrodisiac and immunostimulatory properties. The herbs have been traditionally used as Vajikaran Rasayana herbs because of their putative positive influence on sexual performance in humans. Lyophilized aqueous extracts obtained from the roots of A. racemosus, C. borivilianum, and rhizomes of C. orchioides were studied for sexual behavior effects in male albino rats and compared with untreated control group animals (total N = 60). The rats were evaluated for effect of treatments on anabolic effect. Seven measures of sexual behavior were evaluated. Administration of 200 mg/kg body weight of the aqueous extracts had pronounced anabolic effect in treated animals as evidenced by weight gains in the body and reproductive organs. There was a significant variation in the sexual behavior of animals as reflected by reduction of mount latency, ejaculation latency, post ejaculatory latency, intromission latency, and an increase of mount frequency. Penile erection (indicated by Penile Erection Index) was also considerably enhanced. Reduced hesitation time (an indicator of attraction towards female in treated rats) also indicated an improvement in sexual behavior of extract treated animals. The observed effects appear to be attributable to the testosterone-like effects of the extracts. Nitric oxide based intervention may also be involved as observable from the improved penile erection. The present results, therefore, support the folklore claim for the usefulness of these herbs and provide a scientific basis for their purported traditional usage.

The advantage of social living: brain neuropeptides mediate the beneficial consequences of sex and motherhood

Living in social groups is clearly beneficial for many species, often resulting in increased survival, enhanced fitness of the group, and progression of brain development and cognitive abilities. The development of the social brain has been promoted on the basis (i) of activation of reward centres by social stimuli, (ii) of positive consequences of close social interactions on emotionality (which is reinforcing by itself) and on general fitness, and (iii) of negative health consequences in the absence or as a result of sudden interruption of social interactions. For example, social interactions as seen between mother and child or between mating partners have beneficial effects on the mental and physical health state, in particular on adaptive processes related to emotional and physiological stress coping in both sexes. Here, the neurobiological basis of social behaviour, in particular the involvement of the brain neuropeptides, oxytocin and prolactin, in mediating such positive health effects will be discussed.

Demographic, physical and lifestyle factors associated with androgen status: the Florey Adelaide Male Ageing Study (FAMAS)

OBJECTIVE

Plasma androgen levels are inversely associated with health in men, the age-related decline of which may result from factors other than ageing per se. This study aimed to determine the effects of demographic, physical and lifestyle factors on age-related androgen status in men.

DESIGN

An observational survey of a regionally representative male population residing in the North West regions of Adelaide, Australia.

PARTICIPANTS

Study sample includes 1195 men aged 35-81 years with a response rate of 45.1%.

MEASUREMENTS

Plasma levels of total testosterone (TT), bioavailable testosterone (BT), SHBG, insulin-like peptide 3 (INSL3), and gonadotrophins were measured along with an extensive list of demographic, physical and lifestyle factors including body composition, muscle strength and biomarkers of chronic diseases, physical activity, nutrition and smoking behaviour.

RESULTS

Low TT was mostly associated with high abdominal fat and triglycerides and low muscle strength rather than ageing per se. Low BT was associated with increased age followed by high whole body fat percentage. BT and TT levels were higher in unmarried men and smokers. SHBG levels increased with age, but were also inversely associated with insulin and triglycerides. The Leydig cell specific factor INSL3 was the strongest biomarker associated with both TT and BT.

CONCLUSIONS

Factors associated with low androgen status variably include high body fat percentage, low muscle strength and biomarkers of the metabolic syndrome. Reducing exposure to factors that adversely affect androgen status may improve the general health of ageing men by mechanisms yet to be defined.

Is the Androgen Deficiency of Aging Men (ADAM) questionnaire useful for the screening of partial androgenic deficiency of aging men?

BACKGROUND

Androgen serum levels significantly decrease in older men, causing quality of life impairment and increasing the risk of chronic disease. This disorder is defined as PADAM (Partial Androgen Deficiency of Aging Men).

OBJECTIVE

To evaluate a PADAM screening tool and determine the prevalence of this disorder in healthy adult men.

METHODS

This was a cross-sectional study in which 96 men aged 40 or more of the South Metropolitan Region of Santiago de Chile were surveyed with the Androgen Deficiency of Aging Men (ADAM) questionnaire of the Saint Louis University and sampled for the serum determination of total testosterone, sexual hormone binding globulin (SHBG) and albumin. Also free and bioavailable testosterone were calculated. PADAM was considered present if items 1 or 7 or any 3 other questions of the ADAM questionnaire were positive. An available testosterone of <198.4 ng/dL was used as a gold standard for the diagnosis of PADAM.

RESULTS

A total of 78 men (81.3%) were identified as possible PADAM according to the ADAM questionnaire. Total testosterone levels fell from 503.6+/-180.1 ng/dL in men aged 40 to 54 years to 382.1+/-247.3 in those >70 years; however this was not statistically significant (ANOVA, p=0.06). In the same age groups, SHBG significantly increased (31.0+/-15.0 to 47.5+/-15.0 nmol/L, p<0.001) whereas free and available testosterone significantly decreased (10.6+/-3.2 to 6.4+/-3.6 ng/dL and 266.6+/-81.2 to 152.2+/-97.6 ng/dL, respectively, p<0.0001). Overall (n=96), available testosterone confirmed PADAM diagnosis in 27 cases (28.1%). The ADAM tool rendered a 83.3% sensitivity and 19.7% specificity in the detection of PADAM. Item 1 (decreased sexual desire) was a better predictor of hypogonadism than the complete questionnaire (63.3% sensitivity and 66.7% specificity).

CONCLUSION

In this series, in accordance to available testosterone, the prevalence of PADAM was determined to be high, in which the ADAM questionnaire rendered a low diagnostic efficiency. PADAM diagnosis could be clinically suspected when symptoms of sexual dysfunction are present.

Androgen administration to aged male mice increases anti-anxiety behavior and enhances cognitive performance

Although androgen secretion is reduced with aging, and may underlie decrements in cognitive and affective performance, the effects and mechanisms of androgens to mediate these behaviors are not well understood. Testosterone (T), the primary male androgen, is aromatized to estrogen (E(2)), and reduced to dihydrotestosterone (DHT), which is converted to 5alpha-androstane, 3alpha, 17beta-diol (3alpha-diol). To ascertain whether actions of the neuroactive metabolite of T, 3alpha-diol, mediates cognitive and affective behaviors, intact, aged male C57/B6 mice (24 month old) as well as young, intact and gonadectomized (GDX; 12 week old) mice were administered s.c. T, 3alpha-diol, E(2), or sesame oil vehicle (1 mg/kg; n=4-5/group) at weekly intervals and 1 h later mice were tested in the activity box, roto-rod, open field, elevated plus maze, zero maze, mirror maze, dark-light transition, forced swim, or Vogel tasks. Mice were trained in the inhibitory avoidance or conditioned contextual fear and were administered hormones following training and then were tested. After the last test occasion, tissues were collected for evaluation of hormone levels and effects on gamma-aminobutyric acid (GABA)-stimulated chloride flux. T, 3alpha-diol, or E(2) increased anti-anxiety and antidepressant behavior of aged, intact mice in the open field, light-dark transition, mirror maze, and forced swim tasks. T or 3alpha-diol, but not E(2), enhanced anti-anxiety behavior in the elevated plus maze, zero maze, and the Vogel task, and increased motor behavior in the activity monitor, latency to fall in the Roto-rod task, and cognitive performance in the hippocampally-mediated, but not the amygdala-mediated, portion of the conditioned fear task and in the inhibitory avoidance task. Anti-anxiety and enhanced cognitive performance was associated with regimen that increased plasma and hippocampal 3alpha-diol levels and GABA-stimulated chloride flux. Similar patterns were seen among young, adult GDX but not in intact mice. Thus, 3alpha-diol can enhance affective and cognitive behavior of male mice.

Predictors of serum testosterone and DHEAS in African-American men

There are few reported data on biochemical and functional correlates of androgen levels in African-American men. This study aimed at reporting physical and biochemical correlates of serum total testosterone (total T), bioavailable testosterone (BT) and dehydroepiandrosterone-sulphate (DHEAS) levels in community-dwelling, African-American men aged 50-65 years. Home-based physical examinations and health status questionnaires were administered to randomly sampled men. Body composition (dual-energy X-ray absorptiometry), lower limb and hand-grip muscle strength, and neuropsychological functions were assessed. Levels of serum total T, BT, DHEAS, oestradiol (E2), adiponectin, leptin, triglycerides and glucose were measured. Multiple linear regression models were constructed to identify factors independently associated with androgen levels. DHEAS levels declined from age 50 to 65 years (p < 0.0001), but total T and BT levels remained constant. Independent of other associated factors, higher total T levels were associated with lower serum triglyceride levels (beta = -0.142, p = 0.049); higher BT was associated with better performance on the trail-making tests (TMT-B:TMT-A ratio: beta = -0.118, p = 0.024) and higher DHEAS levels were associated with lower adiponectin (beta = -0.293, p = 0.047) and higher mini-mental state examination (MMSE) score (beta = 0.098, p = 0.008). Multiple regression models predicted 21, 18 and 29% of variance in total T, BT and DHEAS, respectively. Higher total T levels were associated with serum metabolic markers, particularly lower triglycerides, whereas higher BT was associated with better cognitive and muscle function and DHEAS with lower adiponectin and higher MMSE scores.

Testosterone replacement therapy and prostate cancer: A word of caution

The number of men for whom testosterone is prescribed is rapidly increasing. The aging man normally demonstrates a gradual decline in testosterone. Symptoms of hypogonadism include erectile dysfunction, diminished libido, sarcopenia, increased adiposity, osteopenia and osteoporosis, impaired cognition, and depression. There is a paucity of data regarding both efficacy and safety of testosterone replacement therapy. Testosterone levels have been shown to modulate prostate cancer risk and progression. A prospective evaluation of prostate cancer risk with testosterone replacement therapy has not been conducted. We outline concerns and recommendations for the use of testosterone replacement therapy in the aging man.

Expression characteristics of prostate-derived Ets factor support a role in breast and prostate cancer progression

The purpose of this study was to understand the characteristics of prostate-derived Ets factor (PDEF) protein expression in breast and prostate cancer progression. A polyclonal antibody specific to PDEF was raised and reacted with tissue microarrays consisting of benign breast, in situ ductal, invasive ductal, and invasive lobular breast carcinomas. The antibody was also reacted with tissue microarrays, including benign prostate, prostate intraepithelial neoplasias (PINs), and prostate carcinomas. Increased expression of PDEF was identified in 18%, 50%, 46%, and 51% of benign breast tissues, intraductal, invasive ductal, and invasive lobular carcinomas, respectively. Importantly, in matched samples of benign breast vs tumor, 90% showed higher expression of PDEF in the tumor tissue. Moreover, in invasive breast carcinomas, increased PDEF expression tended to correlate with Her2/neu overexpression. Increased expression of PDEF was also found in 27%, 33%, and 40% of benign prostate tissues, PIN samples, and prostate adenocarcinomas, respectively. Again, in matching samples of cancer vs benign and cancer vs PIN, 68% and 70%, respectively, showed increased expression in the malignant tissue. Moreover, PDEF was found to be more highly expressed in tumors with intermediate or high Gleason score compared with low-grade tumors (P < .01). In addition, R1881 treatment induced PDEF expression in the LNCaP prostate tumor cell line, suggesting regulation of PDEF by androgens in vivo. Together, these results for the first time show frequent increased expression of PDEF protein in breast and prostate tumors and support a role for PDEF in breast and prostate cancer progression.

Sexual experience of male rats influences anxiety-like behavior and androgen levels

There is a wide body of literature to suggest that sexual experience may influence androgen secretion in various species, in turn, androgens may also influence anxiety. We hypothesized that sexual experience may alter anxiety behavior and secretion of endogenous androgens. Experiment 1: anxiety behavior of rats with a history of sexual experience was compared to that of sexually-inexperienced, naïve male rats. Sexually-experienced rats showed less anxiety-like behavior in the open field and elevated plus maze, and exhibited increased plasma and hippocampal testosterone (T) levels. Experiment 2: the effects of recent sexual experience on anxiety behavior of sexually-experienced male rats, sexually-responsive but inexperienced male rats, and sexually-unresponsive, inexperienced male rats exposed to a receptive female immediately prior to testing was examined. Recent sexual experience significantly decreased anxiety-like behavior in the open field, elevated plus maze, and the elevated zero maze tasks, and tended to decrease anxiety-like behavior in the light-dark task. Rats with recent sexual experience exhibited increased plasma and hippocampal T levels. Experiment 3: to examine the effect of recent sexual experience, anxiety behavior of rats with a history of sexual experience that received sexual experience with a stimulus female immediately prior to testing was compared to that of rats with a history of sexual experience that did not receive sexual experience immediately prior to behavioral testing. Experienced rats that were exposed to a female prior to testing showed decreased anxiety-like behavior in the open field, elevated plus maze, and light-dark transition tasks, and showed increased plasma and hypothalamic, T and 3alpha-diol, and increased hippocampal T. Thus, sexual experience is associated with lower levels of anxiety-like behavior and higher levels of androgen secretion.

Intrahippocampal administration of an androgen receptor antagonist, flutamide, can increase anxiety-like behavior in intact and DHT-replaced male rats

Testosterone (T) and its 5alpha-reduced metabolite, dihydrotestosterone (DHT), can decrease anxiety-like behavior; however, the mechanisms underlying these effects have not been established. First, we hypothesized that if T reduces anxiety-like behavior through actions of its 5alpha-reduced metabolite, DHT, then gonadectomy (GDX) would increase anxiety-like behavior, an effect which would be reversed by systemic administration of DHT. Second, we hypothesized that if T and DHT reduce anxiety-like behavior in part through actions at intracellular androgen receptors in the hippocampus, then administration of an androgen receptor antagonist, flutamide, directly to the hippocampus should increase anxiety-like behavior of intact and DHT-replaced, but not GDX, male rats. Inserts that were empty or contained flutamide were applied directly to the dorsal hippocampus of intact, GDX, or GDX and DHT-replaced rats 2 h prior to testing in the open field, elevated plus maze, or defensive freezing tasks. GDX rats exhibited significantly more anxiety-like behaviors than intact or DHT-replaced rats. Intact and DHT-replaced rats administered flutamide to the hippocampus showed significantly more anxiety-like behavior than did intact and DHT-replaced controls. However, flutamide alone did not increase anxiety-like behavior of GDX rats. Together, these findings suggest that androgens can decrease anxiety-like behavior of male rats in part through DHT's actions at androgen receptors in the hippocampus.

Does testosterone have a role in erectile function?

PURPOSE

Despite the well-established role of testosterone in enhancing libido, its exact contribution to erections in men remains unclear. The main objectives of this review are to clarify the role of testosterone in erectile function and evaluate its therapeutic value in men with erectile dysfunction (ED).

METHODS

Review of the relevant literature (English, French, and Spanish) from 1939 to June 2005 was conducted using data sources from MEDLINE, endocrinology text books, and hand searching of cross-references from original articles and reviews. Clinical trials, animal studies, case reports, reviews, and guidelines of major associations were included.

RESULTS

Animal and preliminary human studies suggest that testosterone may facilitate erection by acting as vasodilator of the penile arterioles and cavernous sinusoids. Following castration, most, but not all, men had partial or complete loss of erection. Hypogonadism is not a common finding in ED, occurring in about 5% of cases, and in general, there is lack of association between serum testosterone levels, when present in normal or moderately low levels, and erectile function. Most trials using testosterone for treatment of ED in hypogonadal men suffer from methodological problems and report inconsistent results, but overall, suggest that testosterone may be superior to placebo. Erectile function is more likely to improve with testosterone therapy in patients with severe degrees of hypogonadism. Testosterone treatment may ameliorate the response to the phosphodiesterase 5 (PDE5) inhibitors in hypogonadal men and men with low-normal serum testosterone. Repeated measurement of morning serum total testosterone is a fairly accurate and easy method to evaluate androgenecity, but measurement of free or bioavailable testosterone is recommended in conditions that alter the levels of sex-hormone-binding globulin (SHBG), such as in the elderly and in obesity.

CONCLUSIONS

Available data suggest that in most men circulating levels of testosterone, well below the normal range, are essential for normal erection and that higher levels of serum testosterone may not have major impact on erectile function. Screening for hypogonadism in all men with ED is necessary to identify cases of severe hypogonadism and some cases of mild to moderate hypogonadism, who may benefit from testosterone treatment.

Testosterone's anti-anxiety and analgesic effects may be due in part to actions of its 5alpha-reduced metabolites in the hippocampus

Although testosterone (T) may have effects to enhance analgesia and reduce anxiety, its effects and mechanisms are not well understood. We hypothesized that if T's anti-anxiety and analgesic effects are due in part to actions of its 5alpha-reduced metabolite (dihydrotestosterone-DHT) and/or its 3alpha-hydroxysteroid dehydrogenase reduced metabolite (3alpha-androstanediol-3alpha-diol), in the hippocampus, then androgen regimens that increase levels of these metabolites in the hippocampus should produce anti-anxiety behavior, and analgesic effects, in gonadectomized (GDX) male rats. In Experiment 1, GDX rats were administered T, DHT, 3alpha-diol (1 mg/kg, SC), or vehicle. In Experiment 2, GDX rats had T, DHT, 3alpha-diol-containing inserts, or empty control inserts applied to the dorsal hippocampus immediately prior to behavioral testing. Androgen-administered rats (SC or intrahippocampal) showed significantly more exploratory behavior in the open field and elevated plus maze, less freezing in response to shock, and longer tailflick and pawlick latencies. These findings suggest that T's anti-anxiety effects may be due in part to actions of its 5alpha-reduced metabolites in the dorsal hippocampus.

Normal, bound and nonbound testosterone levels in normally ageing men: results from the Massachusetts Male Ageing Study

OBJECTIVE

There is little consensus on what androgen levels are 'normal' for healthy, ageing men. Using data from the Massachusetts Male Ageing Study (MMAS), we estimated age-specific, normal androgen levels for men aged 40-79 years while accounting for health status and behavioural factors known to influence hormone levels.

DESIGN

Prospective, observational study.

PATIENTS

Community-based random sample of men aged 40-79 years: n = 1677 men studied at T1 (1987-1989), n = 1031 at T2 (1995-1997) and n = 631 at T3 (2002-2004), for a total of 3339 observations. The average number of years between the T1 and T2 interviews was 8.8 (range 7.1-10.4 years) and 6.4 (range 5.6-7.9 years) between T2 and T3.

MEASUREMENTS

Serum total testosterone (T) and sex hormone-binding globulin (SHBG) were measured on nonfasting blood samples collected within 4 h of subject's awakening. Free and bio-available T were calculated from T and SHBG using the Sodergard equation. Trained interviewers administered an in-home questionnaire of health, medication and lifestyle. Participants were considered apparently healthy if all of the following were met: (i) absence of self-reported chronic disease (diabetes, heart disease, high blood pressure, cancer, ulcer); (ii) not on prescription medication believed to affect hormone levels; (iii) body mass index (BMI) not exceeding 29 kg/m2; (iv) alcohol consumption less than or equal to six drinks/day; and (v) nonsmoking.

RESULTS

Chronic disease and high BMI significantly decreased whereas smoking tended to increase total, free and bio-available T concentrations. Apparently healthy men had significantly higher median hormone concentrations at most time points than did not apparently healthy men. Due to the opposite effects of smoking and the other components of the definition, apparently healthy men were compared to nonsmoking, apparently unhealthy men. The former group had significantly higher androgen levels (Wilcoxon rank-sum P-values ranged from 0.01 to 0.0001) for all hormones at all interviews. Ninety-five percent of apparently healthy men in their 40s, 50s, 60s and 70s would be expected to have total T in the range (2.5-97.5th percentile): 8.7-31.7, 7.5-30.4, 6.8-29.8 and 5.4-28.4 nm (251-914, 216-876, 196-859, 156-818 ng/dl), respectively.

CONCLUSIONS

Age, health and lifestyle factors impact androgen levels and should be accounted for in calculations of normal reference ranges. We propose the following age-specific thresholds, below which a man is considered to have an abnormally low total T: 8.7, 7.5, 6.8 and 5.4 nm (251, 216, 196 and 156 ng/dl) for men in their 40s, 50s, 60s and 70s, respectively. These cutoffs correspond to the 2.5th percentile in our data; thus, approximately 2.5% of men aged 40-79 years would have abnormally low T levels based on hormone levels alone.

Hormonal fountains of youth

Any hope of a fountain of youth to stop people from getting older is a long way off, with science just beginning to understand the complex genetic, physical, and hormonal causes of aging. Clearly, modem research has demonstrated that the concept of a hormonal fountain of youth is predominantly mythology. The best evidence supporting use of hormonal replacement is vitamin D and estrogen replacement to prevent hip fractures. Other than that, treatment should be limited to hormone replacement in persons who have endocrine disease.

Serum Sex Hormones, IGF-1, and IGFBP3 Exert a Sexually Dimorphic Effect on Lean Body Mass in Aging

BACKGROUND

Endogenous and exogenous sex hormones affect changes in body composition during aging via independent and dependent effects on the growth hormone/insulin-like growth factor-1 (GH/IGF-1) axis and associated binding proteins (BP).

METHODS

Fasting serum IGF-1, IGFBP3, testosterone, estrone, and sex hormone binding globulin were analyzed in 48 women on hormone replacement (HRT) (unopposed oral estrogen, HRT+, 74.0 +/- 6 years), 135 women not on HRT (HRT-, 77.3 +/- 7 years), and 128 healthy men (men, ). Total lean body mass (LBM) and total fat were measured by dual energy X-ray absorptiometry.

RESULTS

Total LBM decreased with age in all groups (p = .05). LBM was greater, and IGF-1, IGFBP3, and testosterone were lower in HRT+ versus HRT- women (p = .02, p = .01, p = .04, and, respectively). LBM in men was positively related to IGF-1 (p = .02) and testosterone (p < .01), whereas LBM was associated with IGFBP3 (p = .04) and total fat (p < .001) in female HRT+ and total fat (p < .01) in HRT- women. IGF-1 decreased with age in men and HRT- women (p < .01) but did not decrease in HRT+ women. Total fat significantly decreased across age (p < .05). Controlling for age and HRT, the rate of decrease in fat was slower in men versus women (p = .02). IGFBP3 decreased in all groups across age (p < .01), and the ratio of IGF-1 to IGFBP3 decreased faster in men compared to HRT+ and HRT- women (p = .02).

CONCLUSIONS

Our data indicate divergent influences of sex steroids, IGF-1, and IGFBP3 on age-related changes in LBM in healthy elderly men and women.