Experimentally induced androgen depletion accentuates ethnicity-related contrasts in luteinizing hormone secretion in asian and caucasian men

Predictors of Chronic LH-Testosterone Axis Suppression in Male Macroprolactinomas With Normoprolactinemia on Cabergoline

CONTEXT

Data are limited regarding prevalence, predictors, and mechanisms of persistent hypogonadotropic hypogonadism (HH) in males with a macroprolactinoma who achieve normoprolactinemia on dopamine-agonist therapy. None of the previous studies provide cutoffs to predict the achievement of eugonadism.

OBJECTIVE

The objective of this work is to evaluate the prevalence of persistent HH and its determinants in men with a macroprolactinoma who achieve normoprolactinemia on cabergoline monotherapy.

DESIGN AND SETTING

This retrospective study with prospective cross-sectional evaluation took place at a tertiary health care center.

PATIENTS

Study participants included men with a macroprolactinoma and baseline HH who achieved normoprolactinemia on cabergoline monotherapy.

MAIN OUTCOME MEASURES

Outcome measures of this study included the prevalence of persistent HH and its predictors.

RESULTS

Thirty participants (age, 38.3 ± 10.1 years) with baseline tumor size of 4.08 ± 1.48 cm and median (interquartile range) prolactin of 2871 ng/mL (range, 1665-8425 ng/mL) were included. Eight of 30 participants achieved eugonadism after a median follow-up of 3 years. Patients with persistent HH had suppression of the luteinizing hormone (LH)-testosterone axis with sparing of other anterior pituitary hormonal axes, including follicle-stimulating hormone-inhibin B. Baseline prolactin (1674 vs 4120 ng/mL; P = .008) and maximal tumor diameter (2.55 ± 0.36 vs 4.64 ± 1.32 cm; P = .003) were lower in patients who achieved eugonadism. Baseline maximal tumor diameter less than or equal to 3.2 cm (sensitivity: 75%, specificity: 63.6%) and serum prolactin less than or equal to 2098 ng/mL (sensitivity: 87.5%, specificity: 77.3%) best predicted reversal of HH.

CONCLUSION

Recovery of the LH-testosterone axis occurred in 26.7% of men with a macroprolactinoma who achieved normoprolactinemia on cabergoline monotherapy. Higher baseline tumor size and serum prolactin predict persistent HH. Our data favor chronic functional modification of the hypothalamic-pituitary-gonadal axis over gonadotroph damage as the cause of persistent HH.

A meta-regression evaluating the effectiveness and prognostic factors of oral phosphodiesterase type 5 inhibitors for the treatment of erectile dysfunction

The effectiveness of phosphodiesterase type 5 inhibitors (PDE5-Is) for erectile dysfunction (ED) varies considerably among trials, but available studies investigating the factors that affect the effectiveness are few and findings are not consistent. A systematic search was performed in PubMed, Cochrane Library, and EMBASE to identify randomized controlled trials comparing PDE5-Is with placebo for the treatment of ED. The methodological quality of included studies was assessed by the Cochrane Collaboration's tool for assessing risk of bias. The associations between prespecified study-level factors and effectiveness were tested by a random effects meta-regression model. This study included 93 trials with 26 139 patients. When all PDE5-Is were grouped together, Caucasian ethnicity was associated with 15.636% (95% confidence interval [CI]: 0.858% to 32.579%) increase in risk ratio (RR) for Global Assessment Questionnaire question-1 (GAQ-1), and 1.473 (95% CI: 0.406 to 2.338) score increase in mean difference (MD) for posttreatment International Index of Erectile Function-Erectile Function domain score (IIEF-EF), compared to Asian ethnicity. A one-score increase in baseline IIEF-EF was associated with −5.635% (95% CI: −9.120% to −2.017%) reduction in RR for GAQ-1, and −0.229 (95% CI: −0.425 to −0.042) score decrease in MD for posttreatment IIEF-EF. In conclusion, PDE5-Is are more effective in Caucasians than Asians, and in patients with more severe ED.

In young men, a moderate inhibition of testosterone synthesis capacity is only partly compensated by increased activity of the pituitary and the hypothalamus

CONTEXT

The classical interpretation of the feedback regulation of the male hypothalamo-pituitary-gonadal axis predicts that a partial inhibition of testosterone (T) synthesis will result in a compensatory rise in LH secretion. The question arises as to whether such a compensation is complete or that decreased T synthesis may result in a lower plasma T concentration.

OBJECTIVE

To investigate whether a moderate inhibition of T synthesis capacity will be fully compensated by increased LH secretion. DESIGN, SUBJECTS AND INTERVENTIONS: In nine young healthy men, we partially inhibited T synthesis capacity using ketoconazole (KTZ) 100 mg four times daily. On day -6 (1 week prior to KTZ intake), days 1 and 8 of KTZ administration blood was drawn [07:00 h (t(1)), 10:00 h (t(2)), 13:00 h (t(3))] for evaluation of T, LH, oestradiol (E2), 17-OH-progesterone (17OHP), progesterone (PR) and sex hormone binding globulin (SHBG). On day 8, 5000 IU of hCG were administered to evaluate the maximal T secretion under KTZ.

RESULTS

Administration of KTZ resulted in an acute, moderate but significant decrease of plasma T concentration. On day 8, plasma LH, 17OHP and PR were elevated relative to day -6 and day 1, but mean T was still lower compared to day -6. Mean E2 and SHBG were only slightly affected by KTZ. After stimulation by hCG, plasma T was restored to its baseline level.

CONCLUSION

These results argue against the assumption that a moderate decline in T synthesis capacity will be compensated completely by increased LH secretion.