Endocrine Diseases
Pituitary
Hypopituitarism
Common causes: tumors, infection, vascular lesions, trauma. Lesion in pituitary gland, stalk, or hypothalamus.
Evaluation: thyroid function tests, prolactin level, assess adrenal reserve (corticotropin [ACTH] stimulation for cortisol responses). Pituitary stimulation tests sometimes useful.
Pituitary Tumors
Most common cause of neurologic symptoms of hypopituitarism. Headache, visual loss, cavernous sinus syndromes with large tumors.
Symptoms only from secreted hormone for microadenomas (<10 mm) or general pituitary dysfunction for macroadenomas (>10 mm).
Prolactinoma: most common cause of clinically manifest hyperprolactinemia. Women: amenorrhea, galactorrhea. Men: impotence, infertility, galactorrhea (rare). Prolactin >200 ng/mL diagnostic of prolactinoma.
Treatment: dopaminergic agonists (e.g., bromocriptine, cabergoline), trans-sphenoidal adenomectomy, radiotherapy.
Other Causes of Hypopituitarism
Pituitary apoplexy: hemorrhage into pituitary tumor. Acute headache, meningismus, visual loss, ocular palsies, altered level of consciousness.
Sheehan syndrome: postpartum necrosis of pituitary. Obtundation, hypotension, tachycardia, hypoglycemia, amenorrhea, failure to lactate. Acute or chronic.
Excessive Growth Hormone and Acromegaly
Acromegaly: slowly progressive, excessive growth of skeleton, soft tissues. Coarse facial features, large hands and feet; gigantism if onset at young age. Usually growth hormone (GH)–secreting pituitary tumor.
Diagnosis: sustained elevation of GH, cannot be suppressed by physiologic stimuli (e.g., glucose); MRI shows tumor.
Treatment: somatostatin analogues, surgical removal.
Excessive Adrenocorticotropic Hormone
Cushing disease: hypersecretion of ACTH by pituitary tumor. Plethoric round face, centripetal obesity, abdominal striae, hypertension, diabetes mellitus, amenorrhea, hirsutism, acne, osteoporosis. Mental status changes, myopathy sometimes.
Laboratory data: elevated urinary free cortisol levels; cortisol secretion suppressed by dexamethasone.
Treatment: trans-sphenoidal pituitary adenomectomy.
Diabetes Insipidus (DI)
Excessive excretion of urine (polyuria), abnormally large fluid intake (polydipsia) from diminished antidiuretic hormone (vasopressin) in posterior pituitary. Hypothalamic dysfunction primary (idiopathic) or secondary (tumor, aneurysm, xanthomatosis, sarcoid, trauma, infections, stroke).
Laboratory data: low urine specific gravity; decreased urine output after vasopressin injection (vs. nephrogenic DI); urine-specific gravity increases with water restriction (vs. psychogenic polydipsia).
Treatment: tumor resection; desmopressin (1-desamino-8-darginine vasopressin, DDAVP).
Excessive Secretion of Antidiuretic Hormone (ADH)
Syndrome of inappropriate ADH secretion (SIADH). Hypothalamo-hypophyseal pathology (head injury, infection, tumor). Also with remote lung carcinoma, other lung disease, drugs (e.g., carbamazepine).
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