Deficiency of one or more anterior or posterior pituitary hormones; postpartum hemorrhage-induced infarction is Sheehan syndrome.
Also known as: hypopituitarism, panhypopituitarism, Sheehan syndrome, pituitary apoplexy, anterior pituitary failure, pituitary insufficiency
Overview
Partial or complete deficiency of one or more pituitary hormones. Panhypopituitarism refers to deficiency of all anterior pituitary hormones (ACTH, TSH, LH, FSH, GH, prolactin) with or without posterior pituitary involvement (ADH, oxytocin). Sheehan syndrome is postpartum pituitary necrosis from hemorrhagic hypotension causing infarction of an enlarged, vulnerable pregnancy gland.
Epidemiology
Estimated prevalence 45 per 100,000. Most commonly caused by pituitary adenomas and their treatment in high-income settings. Sheehan syndrome remains a common cause in regions with limited obstetric care; reported incidence has fallen markedly with modern obstetric practice in resource-rich countries.
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Question 1EndocrineMedium
A 31-year-old woman presents with 8 months of progressive fatigue, cold intolerance, and loss of libido. She delivered her first child 8 months ago, a course complicated by severe postpartum hemorrhage requiring transfusion and a brief episode of hypotension. She was never able to breastfeed and has not resumed menses. On exam, blood pressure is 92/58 mm Hg with orthostatic drop, skin is pale and fine, and she has sparse axillary and pubic hair without hyperpigmentation. Labs show sodium 129 mEq/L, low free T4 with a TSH of 0.8 mU/L, low 8 AM cortisol, and low LH, FSH, and estradiol. Which of the following is the most likely diagnosis?
AHereditary hemochromatosis
BSevere primary hypothyroidism
CPrimary adrenal insufficiency
DSheehan postpartum necrosis
Reveal answer & full explanation
Correct answer: D — Sheehan postpartum necrosis
AHereditary hemochromatosis
BSevere primary hypothyroidism
CPrimary adrenal insufficiency
DSheehan postpartum necrosis✓
Why Sheehan postpartum necrosis is correct
Postpartum pituitary necrosis follows severe peripartum hemorrhage and hypotension, which infarcts the enlarged, metabolically demanding pregnancy gland.
The picture is classic central (secondary) panhypopituitarism: failure to lactate is the earliest, most specific sign, followed by failure to resume menses and insidious fatigue.
The labs confirm a central pattern: low free T4 with an inappropriately normal/low TSH, low cortisol, and low gonadotropins with low estradiol — multiple trophic hormones are low, pointing to pituitary failure rather than a single end-organ.
Hyponatremia reflects glucocorticoid deficiency, and the absence of hyperpigmentation and hyperkalemia argues against a primary adrenal process.
Why the others are wrong
Primary adrenal insufficiency — Addison disease causes hyperpigmentation, hyperkalemia, and an ELEVATED ACTH; it would not explain the simultaneous central hypothyroidism and hypogonadism seen here.
Severe primary hypothyroidism — would show an ELEVATED TSH with low free T4, not the low/inappropriately normal TSH in this patient, and does not produce combined cortisol and gonadotropin deficiency.
Hereditary hemochromatosis — iron deposition can cause hypopituitarism, but it presents with elevated ferritin/transferrin saturation and features such as arthropathy, diabetes, and hepatic disease, not an acute postpartum-hemorrhage trigger with failure to lactate.
Question 2EndocrineMedium
A 31-year-old woman presents 4 months after a delivery complicated by severe postpartum hemorrhage requiring transfusion. She reports she was never able to breastfeed and has not resumed menses. Over the past several weeks she has had worsening fatigue, anorexia, and lightheadedness on standing. Blood pressure is 92/58 mm Hg with orthostatic changes, and the skin appears pale without hyperpigmentation. Laboratory studies show sodium 129 mEq/L, potassium 4.1 mEq/L, and a low 8 AM serum cortisol. Which of the following additional findings best supports the diagnosis of hypopituitarism?
AHigh plasma ACTH concentration level
BHigh plasma renin activity level
CHigh serum potassium concentration
DLow plasma ACTH concentration level
Reveal answer & full explanation
Correct answer: D — Low plasma ACTH concentration level
AHigh plasma ACTH concentration level
BHigh plasma renin activity level
CHigh serum potassium concentration
DLow plasma ACTH concentration level✓
Why Low plasma ACTH concentration level is correct
This patient has secondary (central) adrenal insufficiency from Sheehan syndrome, postpartum pituitary necrosis after hemorrhagic hypotension.
In central disease the pituitary fails to drive the adrenal, so a low 8 AM cortisol is paired with a low or inappropriately normal ACTH. Low target hormone with a low or inappropriately normal trophic hormone is the hallmark of pituitary-level failure.
It fits the clinical picture: failure to lactate (earliest, most specific Sheehan sign), failure to resume menses, fatigue, hypotension, and hyponatremia.
Why the others are wrong
High plasma ACTH concentration level is the pattern of primary adrenal insufficiency (Addison disease), where the failing adrenal removes negative feedback and ACTH rises; it would also produce hyperpigmentation, which is absent here.
High plasma renin activity level points to mineralocorticoid (aldosterone) deficiency seen in primary adrenal insufficiency. In central disease aldosterone is preserved because it is driven by the renin-angiotensin system rather than ACTH, so renin is not elevated.
High serum potassium concentration reflects aldosterone deficiency in primary adrenal insufficiency; this patient is normokalemic at 4.1 mEq/L because aldosterone is intact, consistent with central rather than primary disease.
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Pituitary apoplexy (hemorrhage or infarction of pre-existing adenoma)
Pathophysiology
Damage to the pituitary gland or hypothalamic-pituitary stalk disrupts trophic hormone secretion. Order of hormone loss in progressive disease (helpful mnemonic 'Go Look For The Adenoma Please'): GH first, then LH/FSH, TSH, ACTH, prolactin (ADH loss occurs only with stalk or posterior pituitary involvement). In Sheehan syndrome, peripartum hyperplasia of lactotrophs increases gland volume and metabolic demand without proportionate increase in arterial supply, predisposing to ischemic necrosis if perfusion drops.
Clinical presentation
Symptoms
Secondary adrenal insufficiency: fatigue, anorexia, weight loss, hypotension, hyponatremia, hypoglycemia (no hyperkalemia or hyperpigmentation because aldosterone and ACTH are not elevated)
Secondary hypothyroidism: fatigue, cold intolerance, constipation, weight gain, dry skin
Hypogonadism: amenorrhea, infertility, decreased libido, erectile dysfunction, loss of body hair, fine wrinkling around eyes and mouth
Growth hormone deficiency in adults: reduced lean body mass, central adiposity, low energy, impaired quality of life
Sheehan-specific: failure to lactate postpartum (earliest sign), failure to resume menses, fatigue out of proportion to postpartum recovery
Postpartum woman who cannot breastfeed, never resumes menses, and develops insidious fatigue, hypotension, and hyponatremia — classic Sheehan syndrome presentation.
Primary hypothyroidism — Elevated TSH with low free T4; central hypothyroidism shows inappropriately normal or low TSH with low free T4
Primary gonadal failure — Elevated LH and FSH with low estradiol or testosterone; central hypogonadism shows low or inappropriately normal gonadotropins
Anorexia nervosa — Functional hypothalamic hypogonadism, low BMI, and behavioral context; reversible with weight restoration
Severe chronic illness (nonthyroidal illness, euthyroid sick syndrome) — Low T3, normal or low TSH and free T4, no clinical hypothyroidism; resolves with recovery
Hemochromatosis — Iron overload affecting pituitary, liver, pancreas, heart; elevated ferritin and transferrin saturation; HFE gene testing
Empty sella syndrome — Incidental imaging finding of CSF-filled sella; most are asymptomatic with normal function
Diagnostic workup
Diagnostic criteria
Combination of low target hormone levels (cortisol, free T4, sex steroids) with low or inappropriately normal trophic hormones (ACTH, TSH, LH, FSH) confirms central deficiency. Provocative testing required when basal values are equivocal.
Labs
8 AM cortisol with simultaneous ACTH; cosyntropin stimulation test if equivocal (peak <18 mcg/dL after 30-60 min suggests adrenal insufficiency)
TSH and free T4 — central hypothyroidism shows low free T4 with low or inappropriately normal TSH
LH, FSH, estradiol (women), 8 AM testosterone (men) — low sex steroids with low or inappropriately normal gonadotropins
Prolactin (low in Sheehan; elevated in stalk effect)
IGF-1 (screening for GH deficiency); confirmatory insulin tolerance test or glucagon stimulation test if symptomatic
Serum sodium, glucose, osmolality; if polyuria, paired serum and urine osmolality with water deprivation test
Imaging
MRI of the sella with and without gadolinium — small or empty sella in Sheehan, mass lesion in adenoma, stalk thickening in hypophysitis or sarcoidosis
Formal visual field testing if any mass or chiasmal symptoms
Clinical response; AM cortisol unreliable on replacement
TSH (thyroid)
Levothyroxine, started AFTER cortisol replacement
Free T4 in upper half of reference range; TSH not useful
LH/FSH (men)
Testosterone cypionate IM, gel, or intranasal
Total testosterone; hematocrit; PSA
LH/FSH (women)
Estradiol + progestin (oral, transdermal)
Symptoms; bone density; menstrual response
GH
Somatropin daily SC
IGF-1 in age-adjusted reference range
ADH (posterior)
Desmopressin intranasal, oral, or SC
Serum sodium, urine output, thirst
Prolactin
No replacement (lactation only)
—
Hormone replacement framework for hypopituitarism — sequence and monitoring.
Treatment
First-line
REPLACE CORTISOL FIRST before thyroid hormone — initiating levothyroxine in a cortisol-deficient patient can precipitate adrenal crisis
Glucocorticoid replacement: hydrocortisone 15-25 mg/day in divided doses (two-thirds AM, one-third afternoon), prednisone 3-5 mg daily, or dexamethasone 0.25-0.5 mg daily — no mineralocorticoid needed because aldosterone secretion is preserved
Stress dosing for illness, surgery, trauma — triple oral dose or IV hydrocortisone 50-100 mg every 6-8 hours
Levothyroxine replacement after cortisol replacement is established — titrate by free T4 (not TSH, which is unreliable in central hypothyroidism)
Sex hormone replacement: testosterone replacement — testosterone cypionate IM, testosterone gel, intranasal testosterone — for men; estradiol with cyclic or continuous progestin for premenopausal women (combined oral contraceptive or transdermal estradiol with oral micronized progesterone)
Second-line / adjunct
Growth hormone replacement — daily subcutaneous somatropin — for confirmed adult GH deficiency with quality-of-life impairment
Desmopressin — intranasal, oral, or subcutaneous — for central diabetes insipidus
Fertility induction: pulsatile GnRH (rare), or gonadotropins — human chorionic gonadotropin (hCG) with recombinant FSH (follitropin alfa, follitropin beta) or human menopausal gonadotropin (menotropins)
Surgery (transsphenoidal resection) or radiation for mass lesions causing the deficiency
Glucocorticoids for acute lymphocytic hypophysitis
Complications
Adrenal crisis — hypotension, hyponatremia, hypoglycemia, shock; precipitated by illness, surgery, or unrecognized cortisol deficiency
Myxedema coma if profound untreated central hypothyroidism
Osteoporosis from chronic hypogonadism and untreated GH deficiency
Cardiovascular disease (increased mortality even on replacement, partly attributed to nonphysiologic glucocorticoid dosing)
Infertility, sexual dysfunction
Hyponatremia from glucocorticoid deficiency and SIADH-like state
PANCE pearls
Always replace cortisol BEFORE thyroid hormone — starting levothyroxine first accelerates cortisol metabolism and can precipitate adrenal crisis.
In central hypothyroidism, free T4 (not TSH) is used to monitor and titrate levothyroxine; aim for free T4 in the upper half of the reference range.
Inability to lactate after delivery is the earliest and most specific feature of Sheehan syndrome — ask every postpartum woman with vague symptoms after hemorrhage about lactation.
Pituitary apoplexy presents with sudden severe headache, visual disturbance, ophthalmoplegia, and altered mental status — it is an endocrine emergency requiring immediate stress-dose glucocorticoids and urgent neurosurgical evaluation.
Educate every patient on stress-dosing rules and provide a medical alert bracelet plus a parenteral hydrocortisone emergency kit (Solu-Cortef 100 mg IM).
References
Endocrine Society 2016 — Hormonal Replacement in Hypopituitarism in Adults: An Endocrine Society Clinical Practice Guideline (Fleseriu et al., J Clin Endocrinol Metab 2016)
Endocrine Society 2016 — Diagnosis and Treatment of Primary Adrenal Insufficiency: An Endocrine Society Clinical Practice Guideline (Bornstein et al., J Clin Endocrinol Metab 2016)
AACE/ACE 2019 — American Association of Clinical Endocrinologists and American College of Endocrinology Disease State Clinical Review: Postoperative Management Following Pituitary Surgery (Woodmansee et al., Endocr Pract 2019)
Pituitary Society 2011 — Pituitary Society Guidelines on the Diagnosis and Management of Pituitary Apoplexy (Rajasekaran et al., Clin Endocrinol 2011)
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