There are few systematic studies of the relationship between blood testosterone concentrations and the symptoms of overt androgen deficiency. Because most testosterone preparations are relatively short-term, the rapid changes in blood testosterone concentrations they cause make it difficult to define any testosterone threshold. By contrast, subdermal testosterone implants provide stable blood testosterone concentrations over days to weeks, while gradually declining to baseline over 5-7 months. Hence, this provides an opportunity to define a blood testosterone threshold for androgen deficiency symptoms by observing androgen-deficient men as their familiar androgen deficiency symptoms return as testosterone pellets slowly dissolve. Among 52 androgen-deficient men who underwent 260 implantations over 5 yr, at the time of return of androgen deficiency symptoms the blood total and free testosterone concentrations were highly reproducible within individuals (F = 0.8, P = 0.49 and F = 1.4, 0.24, respectively) but varied markedly between men (F = 167 and F = 138, both P < 0.001), indicating that each person had a consistent testosterone threshold for androgen deficiency symptoms that differed markedly between individuals. The most reported symptoms of androgen deficiency were lack of energy, lack of motivation, and reduced libido. The symptomatic threshold was significantly lower in men with secondary hypogonadism compared with men with primary or mixed hypogonadism (total, 9.7 +/- 0.5 nmol/liter vs. 11.7 +/- 0.4 nmol/liter and 10.2 +/- 0.3 nmol/liter, P = 0.006; free, 146 +/- 10 pmol/liter vs. 165 +/- 6 pmol/liter and 211 +/- 18 pmol/liter, P = 0.002) but was not affected by the underlying cause of hypogonadism or by specific symptoms of any severity. Despite a wide range in individual thresholds for androgen deficiency symptoms, the mean blood testosterone threshold corresponded to the lower end of the eugonadal reference range for young men. The implications of these observations for the development of more specific quality-of-life measures, as well as for other potential androgen deficiency states such as chronic diseases and aging, remain to be determined.

The 5/4 h MT definition was the most inclusive, but combination with the 10/24 h definition appeared to identify a clinically important patient cohort.

Objective: Androgen deficiency (AD) leads to bone loss and contributes to osteoporotic fractures in men. Although low bone mineral density (BMD) in AD men is improved by testosterone replacement, the responses vary between individuals but the determinants of this variability are not well defined. Design and methods: Retrospective review of dual energy X-ray absorptiometry (DEXA) of the lumbar spine and proximal femur in men with established AD requiring regular androgen replacement therapy (ART). After a DEXA scan all men were treated with testosterone implants (800 mg, , 6 month intervals). Patients were classified as having a congenital, childhood, or post-pubertal onset, as well as according to the adequacy of treatment prior to their first DEXA scan as untreated, partially treated or well treated. Results: Men with AD requiring regular ART (n ¼ 169, aged 46.3^1.1 years, range 22 -84 years) underwent a DEXA scan prior to being treated with testosterone implants (800 mg, ,6 month intervals). In cross-sectional analysis at the time of the first DEXA scan untreated men (n ¼ 24) had significantly reduced age-adjusted BMD at all four sites (L1 -L4, femoral neck, Ward's triangle and trochanter). Well-treated men (n ¼ 77) had significantly better age-adjusted BMD at all four sites compared with those who were partially treated (n ¼ 66) or untreated (n ¼ 24) with their ageadjusted BMD being normalized. In a longitudinal assessment of men (n ¼ 60) who had two or more serial DEXA scans, at the second DEXA scan after a median of 3 years, men who were previously partially treated (n ¼ 19) or untreated (n ¼ 11) had proportionately greater improvements in BMD, significantly for Ward's triangle (P ¼ 0.025) and the trochanter (P ¼ 0.044) compared with men (n ¼ 30) previously well treated. Conclusions: The present study demonstrates a positive relationship between adequacy of testosterone replacement and BMD in men with overt organic AD. Additionally, the BMD of well-treated AD men approximates that of age-matched non-AD controls. The greatest BMD gains are made by those who have been either untreated or partially treated, and optimal treatment over time (median 3 years) normalizes BMD to the level expected for healthy men of the same age.European Journal of Endocrinology 152 881-886