Cryptorchidism

By the age of 5 years both testes should be in the scrotum. After that age the germinal epithelium is increasingly at risk, and lack of descent by puberty is associated with subfertility. Surgical exploration and orchidopexy are usually undertaken but a short trial of HCG occasionally induces descent: an HCG test with a testosterone response 72 hours later excludes anorchia. Intra-abdominal testes have an increased risk of developing malignancy; if presentation is after puberty, orchidectomy is advised.

Klinefelter's syndrome

Klinefelter's syndrome (seminiferous tubule dysgenesis), a chromosomal disorder (47XXY) affecting 1 in 1000 males, involves both loss of Leydig cells and seminiferous tubular dysgenesis. Patients usually present with poor sexual development, small or undescended testes, gynaecomastia or infertility. They are occasionally mentally retarded. Clinical examination shows small pea-sized but firm testes, usually gynaecomastia and often signs of androgen deficiency. Confirmation is by chromosomal analysis. Treatment is androgen replacement therapy unless testosterone levels are normal. No treatment is possible for the abnormal seminiferous tubules and infertility.

Kallmann's syndrome

This is isolated GnRH deficiency. It is often associated with decreased or absent sense of smell (anosmia), and sometimes with other bony (cleft palate), renal and cerebral abnormalities (e.g. colour blindness). It is often familial and is usually X-linked, resulting from a mutation in the KAL1 gene which encodes anosmin-1 (producing loss of smell); one sex-linked form is due to an abnormality of a cell adhesion molecule. Management is that of secondary hypogonadism. Fertility is possible.

Oligospermia or azoospermia

These may be secondary to androgen deficiency and can be corrected by androgen replacement. More often they result from primary testicular diseases, in which case they are rarely treatable.

Azoospermia with normal testicular size and low FSH levels suggests a vas deferens block, which is sometimes reversible by surgical intervention.