Snapshot A 31-year-old man presents to his primary care physician for the evaluation of infertility. He and his wife have been trying to become pregnant for over a year. His wife was extensively evaluated, which showed no reason on her end for their inability to conceive. Upon further questioning, the patient reports decreased spontaneous erections, breast discomfort, and a reduced need to shave. On physical examination, the patient has a eunuchoid body habitus, gynecomastia, and small testes. On laboratory testing, there is a elevated follicle-stimulating hormone (FSH) and luteinizing hormone (LH) with a low testosterone level. The patient is prescribed testosterone replacement therapy after testing his hematocrit and prostate-specific antigen (PSA) level. (Klinefelter syndrome) Introduction Mechanism of action login to view 6 more bullets Clinical use login to view 28 more bullets Adverse effects login to view 11 more bullets