PURPOSE: Boys with cryptorchidism have overall increased gonadotropin and decreased serum inhibin B levels compared to normal. Serum inhibin B levels, produced by Sertoli cells, may reflect the state of germinative epithelium in cryptorchid testes. We evaluated whether serum inhibin B levels differed between boys with unilateral vanished testis and those with unilateral cryptorchidism.

MATERIALS AND METHODS: Blood samples from 297 boys 1.5 to 5 years old were included, of whom 222 had unilateral cryptorchidism, 29 had unilateral vanished testis and 46 had undergone unilateral orchiopexy 1 year previously. Serum inhibin B levels were measured using a commercially available ELISA kit and were compared to normal range.

RESULTS: Serum inhibin B levels in boys with unilateral vanished testis were not different from those with unilateral cryptorchidism. Serum inhibin B values were above the normal median in 43% of boys previously operated on for unilateral cryptorchidism, compared to 17% at surgery (p = 0.0003). The percentage of patients with inhibin B levels below normal range was 14% in those with unilateral vanished testis, 23% in those with unilateral cryptorchidism and 11% in those who had undergone orchiopexy 1 year previously for unilateral cryptorchidism. The percentage of boys with inhibin B levels above normal median was 24% in those with unilateral vanished testis, 17% in those with unilateral cryptorchidism and 43% in those who had undergone orchiopexy. However, in boys with a vanished testis the frequency of serum inhibin B above normal median was only 5% before age 1.5 years, after which the rate was 67% (p = 0.0022).

CONCLUSIONS: Our findings may reflect the development of contralateral testicular hypertrophy in boys with unilateral vanished testis. The initial low inhibin B values may be explained by impaired total number of Sertoli cells. Serum inhibin B values also indicated that in 6-month to 5-year-old boys with cryptorchidism orchiopexy was beneficial for the germinative epithelium.