Can we rely on total testosterone measurement to exclude hypogonadism in erectile dysfunction?

Although male hypogonadism (MH) is a prevalent comorbidity in patients presenting for erectile dysfunction (ED), its screening relies solely on total testosterone (TT). Ageing and other conditions can increase sex hormone-binding globulin (SHBG) and lower free testosterone (FT) causing symptomatic MH despite normal TT. The primary objective was to measure the prevalence of normal TT/low FT among patients presenting for ED. From January 2019 to December 2020, 408 patients referred for sexual dysfunction were screened; 180 men with a confirmed diagnosis of ED were included. MH was screened using TT, SHBG, albumin and LH. FT was calculated (cFT). Low TT, high SHBG and low cFT were defined as <345 ng/dL, >50 nmol/L and <6.5 ng/dL, respectively. Patients were divided into groups according to TT/cFT status and to age group. The frequency of normal TT/low cFT was 17.2%. From all 31 patients with normal TT/low cFT, only four (12.9%) had either hyperthyroidism, hepatic disease or HIV infection, while 23 (74.2%) were older than 60 years. Patients with normal TT/low cFT were older (65.57 +/- 10.43 vs. 56.79 +/- 10.63 yo, p = 0.001) and had higher SHBG (78.48 +/- 40.14 vs. 52.35 +/- 20.39 nmol/L, p = 0.014) than patients with normal TT/cFT. Patients over 60 years represented 48.9% of the sample, 52.5% had elevated SHBG and their frequency of normal TT/low cFT was 26.3%. Normal TT/low cFT is frequent and can be missed by current screening recommendations for MH in patients presenting for ED. Ageing seems to be the main culprit as elevated SHBG prevalence increases steeply after the sixth decade. TT cannot solely be relied on to exclude biochemical MH in patients presenting for ED, especially in patients over 60 years old. Current guidelines for MH screening in ED should be amended.