How to define hypogonadism? Results from a population of men consulting for sexual dysfunction.

Abstract

The thresholds for testost erone (T) and the symptoms required for defining late onset hypogonadism (LOH) are under debate. The aims of the study are: (1) to verify the association between total and calculated free T (cfT) and sexual symptoms and (2) to identify thresholds for total and calculated free T to discriminate symptomatic from asymptomatic men. A consecutive series of 4890 men attending the outpatient clinic for sexual dysfunction was retrospectively studied. Biochemical parameters were collected. The relationships between symptoms and total or calculated free T were evaluated as LOESS curves. Severe impairment in morning erections, low libido and ED were reported by 14.6, 2.7 and 60.2 %, respectively. Simultaneous presence of severe ED and impaired morning erections or low desire was reported by 12.7 and 1.9 %, respectively. Severely reduced desire and morning erections were complained of by 1.0 %. The simultaneous presence of the three severe sexual symptoms was reported by 0.8 %. Receiver operating characteristic (ROC) curve analysis showed that the highest accuracy for total T and cfT in detecting subjects with two symptoms was observed for reduced morning erections and desire (area under the ROC curve [AUC] = 0.670 ± 0.04 and 0.747 ± 0.04, for total T and cfT, respectively, both p < 0.0001). The addition of the third symptom, ED, further improved the accuracy (AUC = 0.681 ± 0.05 and 0.784 ± 0.04, for total T and cfT, respectively, both p < 0.0001). The assessment of the Youden index showed that the best thresholds for detecting men with androgen deficiency-related symptoms are 10.4 nmol/L for total T and ranges 225-260 pmol/L for cfT. The simultaneous presence of reduced morning erections and desire is the cluster of symptoms that, along with total T < 10.4 nmol/L or cfT <225 pmol/L, defines LOH in a specific, evidence-based manner.