Hypopituitarism is the partial or complete insufficiency of anterior pituitary
hormone secretion and may result from pituitary or
hypothalamic disease. The reported incidence (12-42 new cases per million per year) and prevalence (300-455 per million) is probably underestimated if its occurrence after
brain injuries (30-70% of cases) is considered. Clinical manifestations depend on the extent of
hormone deficiency and may be non specific, such as
fatigue,
hypotension, cold intolerance, or more indicative such as growth retardation or
impotence and
infertility in GH and
gonadotropin deficiency, respectively.A number of inflammatory, granulomatous or neoplastic diseases as well as traumatic or
radiation injuries involving the hypothalamic-pituitary region can lead to
hypopituitarism. Several genetic defects are possible causes of syndromic and non syndromic isolated/multiple pituitary
hormone deficiencies. Unexplained gonadal dysfunctions, developmental
craniofacial abnormalities, newly discovered empty sella and previous pregnancy-associated
hemorrhage or blood pressure changes may be associated with defective anterior pituitary function.The diagnosis of
hypopituitarism relies on the measurement of basal and stimulated secretion of
anterior pituitary hormones and of the
hormones secreted by pituitary target glands. MR imaging of the hypothalamo-pituitary region may provide essential information. Genetic testing, when indicated, may be diagnostic.Secondary
hypothyroidism is a
rare disease. The biochemical diagnosis is suggested by low serum FT4 levels and inappropriately normal or low basal TSH levels that do not rise normally after TRH.
L-thyroxine is the treatment of choice. Before starting replacement
therapy, concomitant
corticotropin deficiency should be excluded in order to avoid acute
adrenal insufficiency.
Prolactin deficiency is also very rare and generally occurs after global failure of pituitary function.
Prolactin deficiency prevents lactation.
Hypogonadotropic hypogonadism in males is characterized by low
testosterone with low or normal LH and FSH serum concentrations and impaired spermatogenesis.
Hyperprolactinemia as well as low
sex hormone binding globulin concentrations enter the differential diagnosis.
Irregular menses and
amenorrhea with low serum
estradiol concentration (<100 pmol/l) and normal or low
gonadotropin concentrations are the typical features of
hypogonadotropic hypogonadism in females. In post menopausal women, failure to detect high serum
gonadotropin values is highly suggestive of the diagnosis. In males, replacement
therapy with oral or
injectable testosterone results in wide fluctuations of serum
hormone levels. More recently developed transdermal
testosterone preparations allow stable physiological serum
testosterone levels. Pulsatile
GnRH administration can be used to stimulate spermatogenesis in men and ovulation in women with
GnRH deficiency and normal
gonadotropin secretion.
Gonadotropin administration is indicated in cases of
gonadotropin deficiency or
GnRH resistance but is also an option, in alternative to pulsatile
GnRH, for patients with defective
GnRH secretion.