Idiopathic hypogonadotropic hypogonadism reversal after testosterone replacement in a 34-year-old male

A 34-year-old male presented to the endocrinology clinic with the complaint of the absence of facial, axillary and pubic hairs. Further history revealed absent ejaculations and decreased early morning erections. The patient had no history of headaches, visual problems or anosmia. On physical examination, there were sparse facial, axillary and pubic hairs, bilateral gynaecomastia, stretch penile length of 5 cm and bilateral testicular volume of 10 mL. Laboratory investigations showed low luteinising hormone, follicular stimulating hormone and testosterone with normal prolactin and thyroid profile. MRI of the pituitary gland showed no evidence of pituitary microadenoma or macroadenoma. The patient was started on testosterone injections. After 9 months of testosterone replacement, the patient's testicular size increased to 20 mL bilaterally and his penile length increased to the mean adult size for his age with normal testosterone and luteinising hormone. He was, thus, advised to discontinue testosterone therapy.