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hypopituitarism

Etiology: 1) deficiency of anterior pituitary hormones a) primary pituitary disease 1] pituitary tumors (pituitary adenoma)* 2] surgical ablation of pituitary* 3] radiation of the sella turcica, radioablation of pituitary 4] pituitary infarction a] post-partum pituitary necrosis (Sheehan's syndrome) b] pituitary apoplexy c] lymphocytic hypophysitis 5] rare causes a] primary empty sella b] pituitary abscess c] congenital hypoplasia/aplasia d] genetic deficiency of Pit-1 transcription factor e] blunt trauma [2] b) hypothalamic or pituitary stalk disease 1] Kallmann's syndrome 2] traumatic (accidental, surgical, radiation) 3] inflammatory/infiltrative a] tuberculosis b] sarcoidosis c] histiocytosis-X (Langerhans cell histiocytosis) d] nocardiosis e] actinomycosis f] hemochromatosis 4] vascular a] bleeding disorders (subarachnoid hemorrhage) b] coagulopathy c] vasculitis 5] neoplasms a] primary 1} craniopharyngioma 2} dysgerminoma 3} meningioma 4} glioma 5} ependymoma 6} hamartoma 7} gangliocytoma 8} primary CNS lymphoma b] metastatic (brain metastases) 1} breast cancer 2} lung cancer 6] functional hypothalamic disorder a] hyperprolactinemia 1} drug-induced hyperprolactinemia 2} primary hypothyroidism 3} chest wall lesion 4} renal failure 5} liver failure b] vasopressin (ADH) deficiency; dipsogenic diabetes insipidus c] GnRH suppression 1} weight disorders 2} psychiatric disorders 3} hyperprolactinemia 4} thyroid disorder 5} adrenal disorder 6} incompensated diabetes mellitus d] growth hormone deficiency; emotional deprivation syndrome e] ACTH deficiency 1} glucocorticoid withdrawal 2} critical illness f] TSH deficiency - post correction of hyperthyroidism g] other metabolic causes 1} anorexia nervosa 2} malnutrition 3} hemochromatosis c) extra sella turcica disorder 1] craniopharyngioma 2] other developmental cysts (Rathke cleft cyst) 3] optic glioma 4] meningioma 5] nasopharyngeal carcinoma 6] sphenoid sinus mucocele 7] coronary artery aneurysm d) idiopathic 2) medications a) opioids b) checkpoint inhibitors - nivolumab - ipilimumab - tremelimumab - pembrolizumab 3) tissue resistance to action of anterior pituitary hormones (rare) * most common causes [2] History: - radiation therapy, pituitary surgery - difficult delivery with hemorrhage of hypotension (Sheehan's syndrome) Clinical manifestations: 1) most commonly presents as chronic process with insidious onset 2) growth hormone deficiency is the most common clinical manifestation 3) features specific for specific etiologies a) loss of libido, erectile dysfunction, amenorrhea (low FSH/LH) b) fatigue, nausea, vomiting, weight loss, abdominal pain (low ACTH) c) cold intolerance, weight gain, and dry skin (low TSH) d) loss of muscle mass (low GH) e) visual field loss* (pituitary mass effect) 4) posterior hormone deficiency - polydipsia, polyuria, nocturia (diabetes insipidus, ADH deficiency) * often bitemporal quadrant visual field defect Laboratory: 1) serum prolactin (> 200 ng/mL confirms prolactinoma) 2) serum IGF-1 (low GH) 3) serum FSH & serum LH a) the most sensitive measures of pituitary function [2] b) serum testosterone or serum estradiol decline with diminished serum FSH & serum LH c) unnecessary in women with normal menstrual cycles 4) serum TSH & free T4 (low in secondary hypothyroidism) 5) testing for central adrenal insufficiency a) serum ACTH low b) serum cortisol low (AM) c) serum sodium & serum glucose may also be low d) cosyntropin-stimulation test 1] generally increased serum cortisol response to ACTH 2] in long-standing secondary adrenal insufficiency, serum cortisol response may be diminished e) metyrapone stimulation test 1] *caution* do NOT perform unless serum ACTH is low 2] diminished response of serum cortisol & serum 11-deoxycortisol 6) see ARUP consult [3] Radiology: - MRI of brain to visualize sella turcica - gadolinium contrast-enhanced MRI neuroimaging of the brain (pituitary protocol) Management: 1) ACTH deficiency resulting in adrenal insufficiency - hydrocortisone* 10-30 mg/day divided BID 2) LH/FSH deficiency a) androgen replacement for hypogonadal men b) estrogen replacement for premenopausal hypogonadal women 3) TSH deficiency: a) replace thyroxine* only after hypoadrenalism has been ruled out or treated b) thyroxine replacement is determined by serum T4, free thyroxine index &/or free T4, not by serum TSH 4) growth hormone deficiency a) adults: start human growth hormone 200-300 ug SQ QD b) increment by 200 ug at monthly intervals c) adjust to maintain serum IGF-1 levels in midnormal range d) women receiving oral estrogens require higher doses [2] 5) vasopressin deficiency - desmopressin* - metered nasal spray 10-20 ug once or twice daily - tablets 0.1-0.4 mg every 8-12 hours - injection 1-2 ug SQ or IV every 6-12 hours * essential for panhypopituitarism; deficiencies can be fatal

Related

pituitary (hypophysis) pituitary hormone pituitary neoplasm

Specific

ACTH deficiency (central adrenal insufficiency) hyposomatotropism (growth hormone deficiency) LHRH deficiency (gonadotropin-releasing hormone deficiency)

General

sign/symptom pituitary disease hormone deficiency

References

  1. Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 187-191
  2. Medical Knowledge Self Assessment Program (MKSAP) 11, 14, 15, 16, 17, 18. American College of Physicians, Philadelphia 1998, 2006, 2009, 2012, 2015, 2018, - Medical Knowledge Self Assessment Program (MKSAP) 19 Board Basics. An Enhancement to MKSAP19. American College of Physicians, Philadelphia 2022
  3. ARUP Consult: Hypopituitarism The Physician's Guide to Laboratory Test Selection & Interpretation https://www.arupconsult.com/content/hypopituitarism - Hypopituitarism (Anterior Pituitary) Testing Algorithm https://arupconsult.com/algorithm/hypopituitarism-anterior-pituitary-testing-algorithm
  4. Toogood AA, Stewart PM. Hypopituitarism: clinical features, diagnosis, and management. Endocrinol Metab Clin North Am. 2008 Mar;37(1):235-61 PMID: 18226739
  5. Darzy KH, Shalet SM. Hypopituitarism following radiotherapy. Pituitary. 2009;12(1):40-50 PMID: 18270844
  6. Schneider HJ, Aimaretti G, Kreitschmann-Andermahr I et al Hypopituitarism. Lancet. 2007 Apr 28;369(9571):1461-70. Review. PMID: 17467517