81. A 29-year-old man comes to the physician with his 27-year-old wife because they have been unable to conceive for 1 year. Previous examination of the wife showed no abnormalities. Physical examination shows normal genitalia. His serum testosterone and luteinizing hormone concentrations are within the reference ranges and serum follicle- stimulating hormone concentration is increased. Semen analysis shows decreased sperm count. A decreased serum concentration of which of following is the most likely in this patient? A) Androstenedione B) Dihydrotestosterone C) Estradiol D) Inhibin B E) Sex hormone-binding globulin

81. A 29-year-old man comes to the physician with his 27-year-old wife because they have been unable to conceive for 1 year. Previous examination of the wife showed no abnormalities. Physical examination shows normal genitalia. His serum testosterone and luteinizing hormone concentrations are within the reference ranges and serum follicle- stimulating hormone concentration is increased. Semen analysis shows decreased sperm count. A decreased serum concentration of which of following is the most likely in this patient? A) Androstenedione B) Dihydrotestosterone C) Estradiol D) Inhibin B E) Sex hormone-binding globulin