Craniopharyngioma

Panhypopituitarism is loss of adequate secretion of all anterior pituitary hormones, most often from a large pituitary tumor, apoplexy, Sheehan syndrome, or pituitary surgery. Diagnosis requires biochemical documentation of each axis plus pituitary imaging. Every patient needs lifelong hydrocortisone and levothyroxine replacement, with glucocorticoid always started before, or together with, thyroid hormone to avoid precipitating adrenal crisis.

Central diabetes insipidus is inability of the posterior pituitary to produce adequate antidiuretic hormone, causing free water loss, polyuria, and hypernatremia; common causes include pituitary/hypothalamic tumor, surgery, trauma, and infiltrative disease. Diagnosis is confirmed with a water deprivation test followed by a desmopressin challenge, and treatment is desmopressin (DDAVP) 10-40 mcg intranasally or 0.1-0.4 mg orally, dosed once nightly or twice daily and titrated to control polyuria while avoiding dilutional hyponatremia from over-replacement.

Secondary adrenal insufficiency is ACTH deficiency from pituitary or hypothalamic disease, or most commonly from withdrawal of prolonged exogenous glucocorticoid therapy, causing isolated cortisol deficiency without hyperpigmentation or hyperkalemia because aldosterone secretion is preserved. Lifelong glucocorticoid replacement with hydrocortisone, with dose increases during illness, prevents adrenal crisis.

Growth hormone (GH) deficiency causes short stature in children and a nonspecific syndrome of fatigue, reduced muscle mass, and adverse body composition in adults, usually from hypothalamic-pituitary disease, surgery, irradiation, or head trauma. Diagnosis relies on a low age-adjusted IGF-1 with confirmatory provocative testing when needed, and treatment is daily subcutaneous somatropin titrated to a normal IGF-1, avoided in active malignancy or an untreated pituitary tumor.

A nonfunctioning pituitary adenoma is a benign pituitary tumor, usually of gonadotroph origin, that does not secrete a clinically excessive hormone and presents through mass effect (visual field loss, headache) or hypopituitarism rather than a hypersecretory syndrome. Diagnosis requires excluding hormone excess and screening for hypopituitarism; treatment is observation for a small asymptomatic incidentaloma or transsphenoidal surgery for mass effect, apoplexy, or growth on follow-up.

Prolactinoma is a prolactin-secreting pituitary adenoma, the most common functional pituitary tumor, presenting with hypogonadism and galactorrhea from prolactin excess or with headache and visual loss from mass effect in larger tumors. Diagnosis requires an elevated prolactin with a pituitary mass on dedicated MRI after excluding pregnancy, medication effect, and hypothyroidism, and first-line treatment is a dopamine agonist, most often cabergoline, which lowers prolactin and shrinks the tumor without surgery in most patients.

SIADH is euvolemic hypotonic hyponatremia caused by antidiuretic hormone secretion or action that is inappropriate for the patient's osmotic and volume status. First-line treatment is fluid restriction to about 800-1,000 mL/day, with vasopressin receptor antagonists (vaptans) or hypertonic saline reserved for severe or symptomatic hyponatremia resistant to fluid restriction.

Obesity is a chronic disease of excess adiposity, defined by a body mass index of 30 or greater, that raises risk for type 2 diabetes, cardiovascular disease, sleep apnea, liver disease, and several cancers. Management is staged: lifestyle intervention for all patients, pharmacotherapy after 3 to 6 months of unmet lifestyle goals, and bariatric surgery for a body mass index of 40 or greater or 35 or greater with a comorbidity.