Male Hypogonadism in Children

Klinefelter syndrome is caused by a chromosome abnormality in which boys have 2 X chromosomes and 1 Y chromosome. Boys normally have 1 X and 1 Y. This syndrome is the most common cause of primary hypogonadism.

The testes are often small and firm and produce low amounts of testosterone. Boys tend to be tall with abnormally long arms and legs, may develop breast tissue (gynecomastia), and often have low muscle mass and less facial and body hair compared to other boys. Puberty (sexual maturity) may be absent, delayed, or incomplete.

The syndrome is usually first identified at puberty, when inadequate sexual development is noted, or later, when infertility is investigated.

In cryptorchidism (undescended testes), 1 or both of the testes remain in the abdomen. Usually the testes descend into the scrotum shortly before birth. At birth, about 3% of boys who are born at full term (9 months) have an undescended testis, whereas 30% of boys who are born prematurely have an undescended testis. In most of them, the testes spontaneously descend on their own within the first 4 months of life.

The cause of cryptorchidism is usually unknown, but it can occur in children who have other disorders such as Klinefelter syndrome or Kallman syndrome.

Undescended testes are treated with surgery within the first year of life.

In bilateral anorchia, the testes were likely present during early development in the womb but were absorbed by the body before or shortly after birth.

Without testes, boys cannot produce testosterone or sperm. Without testosterone or sperm, they cannot develop male secondary sexual characteristics (such as facial hair and muscle mass) and are infertile.

Absence of Leydig cells (cells in the testes that normally produce testosterone) leads to the development of partially developed genitals or ambiguous genitals. Ambiguous genitals are not clearly male or female. These birth defects develop because not enough testosterone is produced to stimulate the fetus to develop normal male genitals.

Noonan syndrome is a genetic defect that causes small testes that do not produce enough testosterone. This syndrome is caused by abnormalities in certain genes that may be inherited, or it may occur spontaneously in a developing fetus.

Boys may have underdeveloped or undescended testes. Puberty may be delayed, and young men with Noonan syndrome may have low levels of testosterone and be infertile.

Kallmann syndrome is a genetic disorder that causes delayed puberty and an impaired sense of smell (some have a normal sense of smell). Children who have this syndrome are lacking proper amounts of luteinizing hormone and follicle-stimulating hormone. Affected boys have an unusually small penis and undescended testes.

Panhypopituitarism is a disorder that occurs when the pituitary gland stops producing all hormones. This disorder can occur when the pituitary gland is damaged (such as by a tumor or an injury) or is underdeveloped or poorly formed. Infections and treatment of tumors also can cause panhypopituitarism.

Without pituitary hormones, children may have delayed growth and no sexual development when puberty is expected.

(See also Hypopituitarism.)

Isolated luteinizing hormone deficiency occurs when only one pituitary hormone, luteinizing hormone, is missing. When luteinizing hormone is missing, the testes develop and produce sperm, because these functions are also controlled by follicle-stimulating hormone. However, the testes do not produce enough testosterone, so affected boys do not develop secondary sexual characteristics. Boys do continue to grow and may have abnormally long arms and legs.

Prader-Willi syndrome is a genetic disorder that occurs because part of a chromosome is missing or is malfunctioning. The function of the reproductive organs is abnormally decreased, which limits growth and sexual development. Boys have undescended testes and an underdeveloped penis and scrotum.