Gonadotrophins are often the first of the adenohypophysial hormones to be affected by any lesion.
The symptoms of gonadotrophin deficiency are dependent on the age of the patient. In the young there will be a failure of the development of secondary sexual characteristics and also there will be a delay in the fusion of epiphyses. If treatment is delayed then the patients will have increased longitudinal growth and result in tall stature.
Kallman's syndrome is an inherited condition where there is isolated gonadotrophin defects. The lesion in this syndrome is at the hypothalalmic level, and patients will suffer from anosmia (lack of smell), and facial defects such as cleft palate, hare lip and facial asymmetry.
Fertile eunuch syndrome is a condition found in the male where there is a congenital defect in LH alone. In this condition, LH secretion is sufficient for spermatogenesis but insufficient for the development of secondary sexual characteristics.
In adults, a gonadotrophin deficiency results in a regression of secondary sexual characteristics. In the male the most pronounced features are a loss of pubic and axillary hair, impotence and loss of libido. In the female, the most striking feature is amenorrhoea and atrophy of the external genitalia.
The most common cause of gonadotrophin deficiency is found in young females with amenorrhoea in response to stress. This is found in its most severe form in anorexia nervosa and is usually treated with counselling.
The basis of the diagnosis is to show decreased levels of the gonadotrophins (FSH and LH), with decreased levels of the relevant gonadal hormones. This will distinguish between a gonadotrophin deficiency (low gonadotrophins and gonad hormones) from a primary gonadal problem (high gonadotrophins and low gonad hormones).
The treatment of gonadotrophin deficiency varies depending on whether fertility is an issue. In cases where fertility is not an issue, sex hormones are administered directly to the patients. In the male, testosterone oenanthate is given every two to four weeks (250mg). In females, ethinyloestradiol (and a progestogen) is given daily (20-50µg).
When fertility is an issue, then it is essential that gonadotrophins are used to induce spermatogenesis and ovulation. In the male, combined LH/FSH therapy is used over 4-6 months. In females, ovulation is induced by LH/FSH injections at the relevant times in the cycle. When the lesion, causing the gonadotrophin deficiency, is at the hypothalamic level then a different type of therapy is used. In this type of deficiency, the patient is given a subcutaneous infusion pump that administers pulses of GnRH. The aim of this treatment is to simulate a normal gonadotrophin release pattern. This type of therapy needs to be carefully monitored to avoid multiple pregnancies.