Hypopituitarism
Hypopituitarism is deficiency of one or more pituitary hormones, producing secondary adrenal, thyroid, gonadal or growth-hormone failure; glucocorticoid deficiency is the immediate life threat, so cortisol replacement and stress cover come before thyroid replacement.
Definition
Hypopituitarism is deficiency of one or more pituitary hormones. Anterior deficits cause secondary adrenal insufficiency, secondary hypothyroidism, hypogonadism or growth-hormone deficiency; stalk or hypothalamic disease may also cause AVP deficiency.
First principles
The pituitary is an endocrine relay
The anterior pituitary drives the adrenal cortex through ACTH, the thyroid through TSH, the gonads through LH/FSH and growth through GH. When pituitary output falls, the target-gland hormone is low but its trophic hormone is also low or inappropriately normal rather than appropriately raised. Prolactin may rise with stalk interruption because hypothalamic dopamine inhibition is lost.
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