ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Endocrine Abstracts (2019) 63 P320 | DOI: 10.1530/endoabs.63.P320

Gonadal Function in Human Immunodeficiency Virus (HIV)-Infected Men: comparison between Isotopic Dilution-Liquid Chromatography-Tandem Mass Spectrometry (ID-LC-MS/MS) and Chemiluminescent Immunoassay (CI)

Sara De Vincentis1,2, Maria Chiara Decaroli1,2, Flaminia Fanelli3, Marco Mezzullo3, Chiara Diazzi2, Fabio Morini1, Davide Bertani1, Daniele Santi1,2, Enrica Baraldi4, Simonetta Tagliavini4, Laura Roli4, Tommaso Trenti4, Uberto Pagotto3, Giovanni Guaraldi5 & Vincenzo Rochira1,2

1Unit of Endocrinology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy; 2Unit of Endocrinology, Department of Medical Specialties, Azienda Ospedaliero-Universitaria of Modena, Modena, Italy; 3Endocrinology Unit and Center for Applied Biomedical Research (CRBA), Department of Medical and Surgical Sciences, University of Bologna – S. Orsola-Malpighi Hospital, Bologna, Italy; 4Department of Laboratory Medicine and Anatomy Pathology, Azienda USL of Modena, Modena, Italy; 5Multidisciplinary Metabolic Clinic, Unit of Infectious Diseases, University of Modena and Reggio Emilia, Modena, Italy.

Background: HIV-infection is associated to premature decline of serum T. However, prevalence and biochemical characterization of hypogonadism in HIV-infected men are still to be well defined.

Aim: To evaluate the gonadal status in HIV-infected men by assessing circulating total T (TT) with either ID-LC-MS/MS or CI.

Methods: Prospective, cross-sectional, observational study on HIV-infected men with ongoing Highly Active Antiretroviral Therapy (HAART). Serum TT, gonadotropins and sex hormone-binding globulin (SHBG) were measured by CI (Architect, Abbott, USA). TT was also assessed by a validated in house ID-LC-MS/MS. Free T (FT) was calculated by Vermeulen equation. Hypogonadism was defined as serum TT levels below 320 ng/dl and/or free T levels below 64 pg/ml. Statistical analysis: Parameters were not normally distributed and Mann-Whitney U test, was used to compare continuous variables. Categorical variables were compared using Chi-Square test, while correlations were performed using linear regression models.

Results: 315 consecutive HIV-infected men were enrolled (mean age 45.56±5.61 years; average duration of HIV-infection 16.57±10.45 years). Serum TT levels assessed by LC-MS/MS (mean 652.1+229.1 ng/dl) were significantly lower compared to CI (mean 740.2+274.7 ng/dl) (P<0.0001). As a consequence, prevalence of T deficiency was significantly higher comparing LC-MS-MS to CI (5.4% vs 3.2%, P<0.0001). 56 patients (17.8%) showed SHBG above the normal range (>71.4 nmol/l). Considering calculated FT, the prevalence of hypogonadism was 9.8% using LC-MS/MS and 7.0% using CI, with a significant difference between methodologies (P<0.0001). TT assessed with LC-MS-MS was directly related to TT assessed with CI (Beta=0.956, R2=0.913, P<0.0001), as well as FT (Beta=0.934, R2=0.873, P<0.0001). TT combined with luteinizing hormone (LH) levels was used to classify hypogonadism. By including compensated form of hypogonadism, the prevalence raised to 15.6% for TT and to 17% for FT.

Conclusions: To the best of our knowledge, this is the first properly-designed prospective study aiming to investigate the gonadal status of HIV-infected men with both LC-MS/MS and CI, together with gonadotropins. Notwithstanding the strong correlation found between the two methodologies, the prevalence of hypogonadism results underestimated when CI is used compared to ID-LC-MS/MS in HIV-infected patients. In clinical practice, SHBG for calculated FT is essential for the detection of T deficiency, revealing the real prevalence of hypogonadism in this clinical setting.