Kallmann syndrome

Alternative names
Gonadotropin deficiency; Hypogonadotropic hypogonadism; Secondary hypogonadism

Definition
Hypogonadotropic hypogonadism describes absent or decreased function of the male testis or the female ovary (the gonads). It results from the absence of the gonadal stimulating pituitary hormones FSH (follicle stimulating hormone) and LH (luteinizing hormone).

Causes, incidence, and risk factors

An area of the brain called the hypothalamus secretes hormones (GnRH) which stimulate the pituitary gland. In response to these hormones, the pituitary gland (located near the brain) secretes other hormones (FSH and LH).

These hormones, in turn, stimulate the ovaries (female) and testes (male) to secrete hormones that are responsible for normal sexual development in puberty. Any disruption in this chain reaction or cascade causes a deficiency of the sex hormones and halts normal sexual maturation.

Failure of the hypothalamus is most commonly a result of Kallmann syndrome. Kallmann syndrome is an inherited disorder that usually includes a disorder of the sense of smell. Failure of the pituitary may result from empty sella syndrome, pituitary tumors (craniopharyngioma), head injuries, or other causes.

Symptoms

• lack of development at puberty, incomplete development or significant delay of pubertal development
  
• prepubertal testicular size in adolescence
  
• absence of secondary sexual development (for example, pubic, facial, and underarm hair)
  
• short stature may be associated with some forms of hypogonadism
  
• anosmia (inability to smell)

• levels of various hormones in the blood
  
• GnRH stimulation test (measuring hormone levels after stimulation by injected hormones)
  
• MRI of the head

Treatment depends on the source of the defect.

• intramuscular (IM) testosterone or slow-release testosterone skin patch
  
• estrogen and progesterone pills
  
• GnRH injections

With proper hormonal stimulation, puberty can be induced and fertility may be restored.

Complications

• delayed puberty
  
• infertility
  
• low self-esteem (Children who do not develop puberty changes until late may suffer from comparison with their peers. Lots of emotional support may be helpful.)

Call your health care provider if your child does not enter puberty as expected.

Prevention

Prevention is dependent on the cause. Genetic counseling may be appropriate for individuals with heritable disorders that are associated with hypogonadism. Prevention of serious head injuries reduces the risk of pituitary injury associated hypogonadotropic hypogonadism.

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