Causes of pituitary insufficiency include pituitary adenomas or other intrasellar and parasellar tumors, inflammatory and infectious destruction, surgical removal, radiation-induced destruction of pituitary tissue, traumatic brain injury (TBI), subarachnoid hemorrhage, and postpartum pituitary necrosis (Sheehan syndrome).
Pituitary tumors, or adenomas, are the most common cause of hypopituitarism in adults.
Depletion of pituitary function by tumors occurs via the following mechanisms: primary pituitary destruction and destruction of the hypothalamus.
In primary pituitary destruction, the anterior pituitary is destroyed. The result is deficiency in some or all pituitary hormones. Pituitary tumors, or adenomas, can be secretory or nonsecretory. Approximately 30% of all macroadenomas larger than 10 mm will produce at least 1 hormone. Hypothalamic disease involves destruction of the hypothalamus. This causes a deficiency or loss of hypothalamic regulatory hormone input to the pituitary, resulting in loss of anterior pituitary hormone secretion.