Symptoms of Hypogonadism Caused By 5α-Reductase Inhibitors

Hypogonadism is a disease to cause decreased energy, libido loss, body hair loss, mood depression, muscle volume reduction, and hot flashes [1-3]. 5α-reductase inhibitors (5-ARIs) are administered orally for male pattern alopecia and benign prostatic hyperplasia due to decrease of dihydrotestosterone, a potent male hormone [4]. 5-ARIs are generally known not to cause hypogonadism because 5-ARIs do not decrease total testosterone (TT) [4-8]; decreased testosterone causes hypogonadism. In recent years, 2 reports suggested that 5-ARIs may decrease TT to cause symptoms of hypogonadism [9,10], but there is no report that 5-ARIs caused cold sensation and paresthesia of lower extremities. We here report a patient with strong cold sensation and paresthesia of lower extremities and symptoms of hypogonadism due to 2 types of oral 5-ARIs. The one was finasteride, an imported medicine for personal use, and the other was saw palmetto, an over-the-counter drug in Japan.