Hypogonadism, (shrunken testicles in males, shrunken ovaries in females) is a condition caused by a reduction in the hormones produced by these organs. It a symptom of many serious disorders.

• It is a symptom of Haemochromatosis, although it may not appear in every male patient with the disorder.
• It is almost always seen in those persons who abuse anabolic steroids, including synththetic Testosterone.
• It is a symptom of many types of Heavy metal poisoning, particularly cadmium poisoning.

It can also be caused by Klinefelter syndrome, Turner Syndrome, mumps, defects of the thalmus or pituitary, androgen insensitivity syndrome (which causes male psuedohermaphrotism), Noonan syndrome, diabetes mellitus and Kallman syndrome.

Hypogonadism at NIH

Hypogonadism at Wikipedia

Hypogonadism at Mayo Clinic