Adrenal Insufficiency

Kidneys with small shrunken adrenal glands
In adrenal insufficiency, the adrenal glands cannot make enough cortisol and, in primary forms, aldosterone.
Infographic: adrenal insufficiency causes, crisis and replacement
The page covers low cortisol, primary, secondary and tertiary forms, the adrenal crisis emergency, and hormone replacement.
Cut-away adrenal gland showing cortex and medulla
The outer cortex of the adrenal gland makes cortisol and aldosterone, the hormones that fall short in adrenal insufficiency.

Adrenal insufficiency is a condition in which your adrenal glands — two walnut-sized glands that sit atop each kidney — cannot produce enough of the steroid hormones your body depends on, chiefly cortisol and, in primary forms, aldosterone. Cortisol governs your stress response, keeps blood pressure stable, regulates blood sugar, and quiets inflammation; without it, the body's ability to cope with even ordinary daily demands breaks down. The condition affects roughly 1 in 10,000 people in developed countries, and it spans a wide spectrum — from the rare, life-threatening autoimmune destruction of the adrenal cortex (Addison's disease) to the far more common gradual suppression of the adrenal axis caused by long-term steroid medication use. The key message: adrenal insufficiency is serious but entirely manageable with the right replacement therapy, and people who are correctly diagnosed and properly treated live full, active lives.


Table of Contents

  1. What Adrenal Insufficiency Is
  2. Primary vs Secondary vs Tertiary
  3. Symptoms and the Classic Triad
  4. Underlying Causes
  5. Diagnosis — Lab Tests and Stimulation Testing
  6. Addisonian Crisis — The Emergency
  7. Treatment and Maintenance Therapy
  8. Sick-Day Rules and Stress Dosing
  9. Key Research Papers
  10. Connections
  11. Featured Videos

What Adrenal Insufficiency Is

The adrenal cortex — the outer layer of each adrenal gland — produces three families of steroid hormones: glucocorticoids (chiefly cortisol), mineralocorticoids (chiefly aldosterone), and adrenal androgens (chiefly DHEA-S). Cortisol is arguably the most critical: it is the master stress hormone, released in a surge whenever the body faces illness, surgery, trauma, or even a hard workout. It raises blood glucose to fuel muscles and the brain, tightens blood vessels to maintain pressure, and modulates immune responses. Aldosterone regulates salt and water balance, directly controlling blood pressure and potassium levels. When either or both of these hormones fall short, the physiological consequences cascade quickly.

The control system works through a feedback loop called the hypothalamic-pituitary-adrenal (HPA) axis. The hypothalamus releases corticotropin-releasing hormone (CRH), which prompts the pituitary to release adrenocorticotropic hormone (ACTH), which in turn tells the adrenal cortex to make cortisol. When cortisol levels are adequate, they feed back to suppress both CRH and adrenocorticotropic hormone — a elegant off-switch. Adrenal insufficiency disrupts this loop at one of three levels, which defines its classification into primary, secondary, or tertiary types.

Primary vs Secondary vs Tertiary

Understanding where the breakdown occurs is clinically important because it determines which hormones need replacing and what tests to order.

Symptoms and the Classic Triad

Adrenal insufficiency is notorious for a slow, insidious onset. Symptoms often accumulate over months or years, and because they are nonspecific — fatigue, weight loss, nausea — the diagnosis is frequently delayed. The classic triad of primary adrenal insufficiency is:

  1. Profound fatigue — not ordinary tiredness, but an exhaustion that does not improve with rest, and that worsens markedly during minor illness or stress.
  2. Hyperpigmentation (primary AI only) — a distinctive bronze or tan darkening of the skin even on sun-unexposed areas: palmar creases, knuckles, buccal mucosa (inside the cheeks and gums), surgical scars, pressure points, and the areolae. This is caused by excess ACTH/MSH stimulation of melanocytes. It does not occur in secondary or tertiary AI, where adrenocorticotropic hormone is low.
  3. Orthostatic hypotension — a drop in blood pressure on standing, causing dizziness, lightheadedness, or fainting. In primary AI this is compounded by aldosterone deficiency causing salt and volume depletion; in secondary/tertiary AI it is driven primarily by cortisol deficiency alone.

Other common symptoms include:

Underlying Causes

The causes differ markedly between primary and central (secondary/tertiary) forms.

Primary Adrenal Insufficiency

Secondary and Tertiary Adrenal Insufficiency

Diagnosis — Lab Tests and Stimulation Testing

The diagnosis requires both identifying low cortisol production and — in most cases — confirming it with dynamic testing.

Basal Morning Cortisol

Cortisol peaks in the early morning (roughly 8 AM) due to the circadian rhythm of adrenocorticotropic hormone. A morning serum cortisol drawn at 8–9 AM provides a useful screening result:

The Standard (High-Dose) Cosyntropin (Adrenocorticotropic Hormone) Stimulation Test

This is the gold-standard dynamic test. Synthetic adrenocorticotropic hormone (cosyntropin) 250 µg is given intravenously or intramuscularly, and serum cortisol is measured at 30 and 60 minutes after injection. In a normal adrenal gland, this supraphysiological adrenocorticotropic hormone dose produces a robust cortisol surge.

An important caveat: the high-dose test can miss early or recent secondary AI (where the adrenal gland has not yet atrophied). In this setting, a low-dose cosyntropin test (1 µg) is more sensitive and is preferred by some endocrinologists for evaluating suspected secondary AI.

Distinguishing Primary from Secondary/Tertiary

Addisonian Crisis — The Emergency

An adrenal (Addisonian) crisis is an acute, life-threatening state of absolute glucocorticoid (and often mineralocorticoid) deficiency, usually triggered by a physiological stressor in a person with underlying adrenal insufficiency. It kills if not treated immediately and kills even in modern intensive care if treatment is delayed. Studies of patients on long-term replacement therapy have found about 5–10 crises per 100 patient-years (a 2015 review), with a prospective German study counting 8.3 per 100 patient-years even in educated patients, and it remains a significant cause of preventable death.

Precipitating Triggers

Clinical Features of Crisis

Emergency Treatment

When clinical suspicion is high, the standard protocol starts treatment immediately, without waiting for confirmatory tests. The standard protocol is:

  1. Hydrocortisone 100 mg intravenous (IV) bolus immediately — this single dose is life-saving; a cortisol level is drawn first if that takes less than 5 minutes, but treatment is not delayed to wait for results.
  2. Continuing hydrocortisone — 200 mg/24h by continuous infusion, or 50–100 mg every 6–8 hours by IV/IM injection, for the first 24 hours.
  3. Intravenous saline (0.9% NaCl) — aggressive volume resuscitation (1–2 liters rapidly, then guided by clinical response) to correct hypovolemia and hyponatremia.
  4. Dextrose (5% or 10% glucose in saline) — added if hypoglycemia is present or suspected.
  5. Identify and treat the precipitating cause — antibiotics for infection; no mineralocorticoid (fludrocortisone) is needed acutely because supraphysiological doses of hydrocortisone have sufficient mineralocorticoid activity at these doses.
  6. Taper to maintenance — as the crisis resolves, gradually taper hydrocortisone back to maintenance doses and restart fludrocortisone once oral medication is tolerated.

Waterhouse-Friderichsen Syndrome

Waterhouse-Friderichsen syndrome is a specific, catastrophic cause of bilateral adrenal hemorrhage caused by fulminant meningococcal septicemia (Neisseria meningitidis). It presents with the classic features of meningococcemia — rapidly spreading petechial or purpuric rash, high fever, and cardiovascular collapse — complicated by acute primary adrenal insufficiency from bilateral adrenal gland hemorrhagic infarction. The mechanism is disseminated intravascular coagulation (DIC) and direct bacterial endothelial damage. Mortality is extremely high without immediate combined treatment with antibiotics and high-dose corticosteroids. See our page on Meningitis for the broader context of meningococcal disease.

Treatment and Maintenance Therapy

The goal of maintenance therapy is to replace, as physiologically as possible, the hormones that the adrenal gland can no longer produce. This means mimicking the normal cortisol circadian rhythm and adjusting doses to match physiological demand.

Glucocorticoid Replacement

Hydrocortisone is the preferred glucocorticoid for daily replacement because its short half-life and pharmacokinetics most closely match the natural cortisol rhythm. The Endocrine Society guideline gives the adult dose as 15–25 mg/day in two to three divided doses:

Alternative glucocorticoids (prednisolone, dexamethasone) have longer half-lives and cover the day with once-daily or twice-daily dosing, but their pharmacodynamics make it harder to replicate the normal peak-trough pattern. Novel once-daily modified-release hydrocortisone formulations deliver a controlled morning peak and are available in some countries, with evidence of slightly better metabolic and quality-of-life profiles. Clinicians aim for the lowest effective dose because over-replacement causes weight gain, osteoporosis, glucose intolerance, and the other well-known consequences of chronic glucocorticoid excess.

Mineralocorticoid Replacement (Primary AI Only)

Fludrocortisone — a synthetic mineralocorticoid — is required in primary adrenal insufficiency to replace the absent aldosterone. The standard dose is 0.05–0.2 mg/day as a single morning dose. Patients on fludrocortisone are encouraged to maintain a liberal salt intake (the opposite of the usual cardiovascular advice). The dose is titrated based on blood pressure, serum sodium and potassium, and plasma renin activity — the target is renin in the mid-normal range. Fludrocortisone is not needed in secondary or tertiary AI because the mineralocorticoid axis, controlled by the renin-angiotensin system rather than by adrenocorticotropic hormone, remains intact.

DHEA Replacement (Selected Cases)

Adrenal androgens (DHEA-S) are also deficient in adrenal insufficiency. DHEA supplementation (25–50 mg/day) is not universally recommended by guidelines but may be considered in women with primary AI who have persistent fatigue, low mood, or reduced libido despite optimal glucocorticoid and mineralocorticoid replacement. Evidence for benefit in men is less compelling.

Monitoring on Treatment

Sick-Day Rules and Stress Dosing

This section is arguably the most practically important for patients living with adrenal insufficiency. Guidelines call for every patient to be taught these rules and to carry a steroid card and an emergency injection kit, because the inability to mount a cortisol stress response means that what is a minor illness for a healthy person can be life-threatening.

The Core Rule: When in Doubt, Double

When to Inject and When to Call Emergency Services

A 2015 review of adrenal crisis states that every patient should be provided with an emergency hydrocortisone injection kit (typically hydrocortisone 100 mg vial with syringe, or a pre-filled auto-injector where available) for self-injection. The sick-day rules describe when it is used:

Guidelines call for patients to carry a medical alert card or wear a medical ID bracelet stating their diagnosis and the emergency treatment protocol, so that any healthcare provider treating them in an emergency knows to give hydrocortisone immediately. Emergency physicians unfamiliar with adrenal insufficiency may not recognize a crisis in time.

Common Mistakes Described in the Research

Key Research Papers

  1. Bornstein SR, Allolio B, Arlt W, et al. (2016). Diagnosis and Treatment of Primary Adrenal Insufficiency: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab, 101(2):364–389. — The authoritative Endocrine Society guideline covering diagnosis, replacement regimens, sick-day rules, and crisis management for primary adrenal insufficiency. — PubMed PMID: 26760044 · doi:10.1210/jc.2015-1710
  2. Charmandari E, Nicolaides NC, Chrousos GP. (2014). Adrenal insufficiency. Lancet, 383(9935):2152–2167. — A comprehensive, clinically oriented review of all three types of adrenal insufficiency, including epidemiology, pathophysiology, and long-term management challenges. — PubMed PMID: 24503135 · doi:10.1016/s0140-6736(13)61684-0
  3. Barthel A, Benker G, Berens K, et al. (2019). An Update on Addison's Disease. Exp Clin Endocrinol Diabetes, 127(2-03):165–175. — A review of primary adrenal insufficiency covering recognition, laboratory work-up, and the importance of patient education on emergency procedures. — PubMed PMID: 30562824
  4. Oelkers W. (1996). Adrenal Insufficiency. N Engl J Med, 335(16):1206–1212. — A landmark review that remains a foundational reference, covering the biochemical basis of primary vs secondary AI, diagnostic algorithms, and mineralocorticoid replacement. — PubMed PMID: 8815944
  5. Rushworth RL, Torpy DJ, Falhammar H. (2019). Adrenal Crisis. N Engl J Med, 381(9):852–861. — A focused review of adrenal crisis — triggers, recognition, emergency treatment protocol, and preventive strategies including patient education and sick-day rules. — PubMed PMID: 31461595
  6. Arlt W. (2009). The approach to the adult with newly diagnosed adrenal insufficiency. J Clin Endocrinol Metab, 94(4):1059–1067. — A step-by-step practical guide to the diagnostic work-up, distinguishing primary from secondary causes and initiating replacement therapy in the newly diagnosed patient. — Search PubMed · doi:10.1210/jc.2009-0032
  7. Allolio B. (2015). Extensive expertise in endocrinology. Adrenal crisis. Eur J Endocrinol, 172(3):R115–R124. — A review reporting 5–10 adrenal crises per 100 patient-years in patients on long-term replacement and a crisis mortality of about 0.5 per 100 patient-years; it describes crisis treatment as simple and highly effective and states that every patient should carry an emergency card and an emergency kit for self-injection. — PubMed PMID: 25288693
  8. Hahner S, Spinnler C, Fassnacht M, et al. (2015). High incidence of adrenal crisis in educated patients with chronic adrenal insufficiency: a prospective study. J Clin Endocrinol Metab, 100(2):407–416. — A 2-year prospective study of 423 patients that documented 8.3 crises per 100 patient-years; gastrointestinal infection, fever and emotional stress were the main precipitating causes. — PubMed PMID: 25419882
  9. Reisch N, Arlt W, Krone N. (2011). Health problems in congenital adrenal hyperplasia due to 21-hydroxylase deficiency. Horm Res Paediatr, 76(2):73–85. — Reviews the health problems of congenital adrenal hyperplasia, an inherited deficiency of the 21-hydroxylase enzyme that blocks cortisol production (a different condition from autoimmune adrenal insufficiency). — PubMed PMID: 21597280 · doi:10.1159/000327794
  10. Puar TH, Stikkelbroeck NM, Smans LC, Zelissen PM, Hermus AR. (2016). Adrenal crisis: still a deadly event in the 21st century. Am J Med, 129(3):339.e1–9. — Documents that adrenal crisis mortality remains significant even in contemporary medicine, and identifies failure to stress-dose during illness as the predominant preventable cause. — Search PubMed · doi:10.1016/j.amjmed.2015.08.021
  11. Grossman AB. (2010). The Diagnosis and Management of Central Hypoadrenalism. J Clin Endocrinol Metab, 95(11):4855–4863. — A detailed review of secondary and tertiary adrenal insufficiency, including the often-missed diagnostic challenge of central AI after pituitary surgery and from exogenous steroid withdrawal. — Search PubMed · doi:10.1210/jc.2010-0982
  12. Arlt W, Allolio B. (2003). Adrenal insufficiency. Lancet, 361(9372):1881–1893. — A comprehensive seminal Lancet review covering all aspects of adrenal insufficiency from epidemiology and autoimmune mechanisms through long-term quality of life on replacement therapy. — Search PubMed · doi:10.1016/s0140-6736(03)13492-7
  13. Smans LC, Van der Valk ES, Hermus AR, Zelissen PM. (2016). Incidence of adrenal crisis in patients with adrenal insufficiency. Clin Endocrinol (Oxf), 84(1):17–22. — A retrospective review of 30 years of medical records at one Dutch university hospital, finding 5.2 crises per 100 patient-years in primary, 3.6 in secondary and 15.1 in tertiary (glucocorticoid-induced) adrenal insufficiency; other illnesses (comorbidity) were the most important risk factor, and gastroenteritis and other infections the most common triggers. — PubMed PMID: 26208266 · doi:10.1111/cen.12865

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Connections

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