Reduced post-natal rise of testosterone in plasma of cryptorchid infants.

Plasma testosterone has been studied in 31 full-term male infants born with bilaterally undescended testes (14) or unilaterally undescended testis (17). From 10 to 89 days after birth, the post-natal testosterone rise was significantly lower in the 18 infants who remained cryptorchid at 4 months than in the 13 who underwent spontaneous testicular descensus and in the normal controls. Blunted post-natal Leydig cell secretion in cryptorchids may relate to a primary LH defect and could contribute to the impairment of both testicular descensus and maturation.