Endocrine Abstracts

JOINT3324

Background: Testosterone Replacement Therapy (TRT) in Hypogonadism (Hy) is started when total testosterone (TT) levels fall below 3.5 ng/ml in presence of a suggestive clinic, therefore the technology used to measure serum T levels is relevant. LC-MS/MS is the gold standard for sex steroids measurement, but it is mainly used for research, while IA is routinary used for clinical purpose. The use of LC-MS/MS in clinical labs is increasing, but its impact in the clinics remains unclear. We aimed to investigate the role of LC-MS/MS compared to IA in the diagnosis and management of male Hy.

Methods: A total of 116 Hypogonadotropic (70) or Hypergonadotropic (46) Hypogonadic men were enrolled irrespective of their treatment status, serum TT was assessed by LC-MS/MS and IA, together with SHBG for calculated free testosterone (cfT). Hy was defined according to the Italian Society of Andrology and Sexual Medicine (SIAMS) threshold: serum TT≤3.5 ng/mL and/or cfT<6.5 ng/dl. TT was quantified using CMIA DxI800 Beckman Coulter (IA) and Chrosystems MassChrom® Steroids in Serum/Plasma kit on Sciex CitrineTM (LC-MS/MS); cfT was calculated with the Vermeulen formula.

Results: Untreated and those patients under TRT were respectively 48 and 68, with a mean ± SD age of 45.98±17.56 years and a mean ± SD BMI of 28.09±5.36 kg/m². Serum TT and cfT assessed with LC-MS/MS were directly related to serum TT (R²=0.6748, P < 0.001) and cfT (R²=0.8787, P < 0.001) assessed with IA, but the R² did not show a precise concordance. Accordingly, the prevalence of biochemical Hy was significantly higher with IA than LC-MS/MS, for all Hy patients TT (59.5% vs 46.6%, OR 1.69, P = 0.025) and those untreated (87.5% vs 64.58%, OR 3.84, P = 0.011). A similar result was found even for cfT in all Hy (53.4% vs 39.7%, OR 1.75, P = 0.018) and the untreated ones (79.17% vs 58.33%, OR 2.71, P = 0.030). Correlation between serum TT measured by LC-MS/MS and IA was higher in the low (≤3.5 ng/mL) (R²=0.6877, P < 0.001) than in the normal to high (R²=0.4396, P < 0.001) range of serum TT, suggesting incongruence between the two in patients under T therapy.

Conclusions: IA compared to LC-MS/MS in hypogonadal men overestimates significantly both the prevalence of biochemical Hy and TRT compensation both for TT and cfT. These results highlight the role of LC-MS/MS and SHBG assessments in every day clinical practice in the diagnosis and TRT monitoring of male Hy, avoiding unnecessary medication.