LEYDIG-CELL FAILURE AND HYPOGONADISM IN A 21 YEAR OLD MALE

Abstract

A 21 year old male, with normal stature and an XY karyotype, presented with sparse pubic hair, no axillary hair, microphallus and otherwise normal external genitalia. Leydig-cell dysplasia and tubular degeneration were found on testicular biopsy. The mean 24 hr. plasma luteinizing hormone (LH) and follicle stimulating hormone (FSH) concentrations were 50 and 8 mIU/ml respectively. LH levels were higher during sleep than during waking hours. There were no sleep-wake differences in FSH levels. Plasma LH rose to 115 mIU/ml in response to 25 μg of LH releasing factor (LH-RF). Plasma FSH responded poorly to LH-RF. The mean 24 hr. plasma concentrations of testosterone (T) and dihydrotestosterone (DHT) were 95 and 84 ng/dl respectively. Plasma T rose from 120 to 160 ng/dl in response to 20,000 units of human chorionic gonadotropin (HCG), given over a 4 day period. Following an additional 20,000 units of HCG, given in 4 equal weekly doses, the plasma T concentration was 120 ng/dl. These data show that this patient has an unusual form of testicular degeneration characterized by diminished T production and poor T response to HCG. Normal concentrations of FSH suggest sufficient Inhibin production. The concentrations of T and DHT in utero, must have been adequate to enable normal differentiation of the external genitalia. This patient's abnormality fits into a spectrum of anomalies with Leydig-cell agenesis at one end and premature Leydig-cell failure (early climacteric) at the other.