Adrenocortical Insufficiency

Core concept: Adrenal insufficiency is inadequate cortisol production or availability. Primary adrenal failure often impairs both cortisol and aldosterone; central insufficiency primarily reflects deficient ACTH drive, with mineralocorticoid activity often maintained.

Key clinical distinction: Primary disease typically causes low cortisol, high ACTH, and potentially hyperkalemia and hyperpigmentation. Central disease generally lacks marked ACTH-driven pigmentation and usually preserves aldosterone.

Clinical priority: Suspected adrenal crisis is a medical emergency. Draw cortisol and ACTH if doing so does not delay treatment, then provide immediate glucocorticoid and hemodynamic resuscitation according to emergency protocols (Bornstein et al., 2016).

Etiology and Epidemiology

Autoimmune adrenalitis is a leading cause of primary adrenal insufficiency in many high-resource settings and may coexist with type 1 diabetes or autoimmune thyroid disease. Other primary causes include infection, hemorrhage, infiltrative disease, bilateral adrenal injury or resection, and inherited disorders. Central insufficiency follows pituitary or hypothalamic disease and commonly occurs after prolonged glucocorticoid exposure suppresses the hypothalamic–pituitary–adrenal axis (Else & Hammer, 2019).

Three levels of deficiency: Primary adrenal insufficiency results from cortical destruction or failure (commonly autoimmune in some populations, but infection, hemorrhage, and infiltrative disease matter). Secondary insufficiency reflects deficient pituitary ACTH. Tertiary insufficiency follows reduced hypothalamic CRH signaling or HPA-axis suppression, often after chronic glucocorticoid exposure. Central forms usually preserve aldosterone because renin–angiotensin signaling remains operative.

Pathophysiology

Cortisol supports vascular responsiveness to catecholamines, gluconeogenesis, substrate mobilization, and stress adaptation. Cortisol deficiency contributes to fatigue, weakness, low glucose, impaired vascular tone, and shock under stress.

Mechanistic synthesis: Cortisol deficiency decreases catecholamine-responsive vascular tone and gluconeogenic reserve while permitting more vasopressin-mediated water retention, explaining hypotension, vulnerability to hypoglycemia, and dilutional hyponatremia. Primary cortical destruction also reduces aldosterone, leading to sodium wasting, hyperkalemia, and possible acidosis. Central ACTH deficiency usually preserves renin-driven aldosterone secretion; ACTH/POMC-derived melanocortin activity explains the hyperpigmentation distinctive of many primary cases (Else & Hammer, 2019).

Clinical Manifestations

Insidious disease may cause anorexia, nausea, vomiting, weight loss, abdominal pain, fatigue, salt craving, orthostasis, or pigmentation changes. A stressor such as infection, surgery, injury, or interruption of steroid replacement can precipitate profound hypotension, refractory shock, altered mentation, hypoglycemia, and electrolyte derangement.

Diagnostic Evaluation

An early-morning serum cortisol with simultaneous ACTH can help localize suspected disease. A very low morning cortisol heightens concern, but intermediate values need context and often cosyntropin stimulation testing. Cortisol response thresholds depend on the assay and protocol; an older universal peak cutoff must not be used uncritically. Recent glucocorticoids, estrogen-related binding changes, and acute illness can complicate interpretation (Penman et al., 2023; Polomoff et al., 2026).

Primary failure is supported by low cortisol with elevated ACTH; measure renin, aldosterone, sodium, potassium, and 21-hydroxylase antibodies when autoimmune primary adrenalitis is suspected. Central failure is associated with low/inappropriately normal ACTH and may require pituitary evaluation. Imaging is guided by the biochemical and etiologic differential, not used as an initial replacement for hormone evaluation (Bornstein et al., 2016).

Cosyntropin tests the adrenal gland’s ability to produce cortisol after ACTH stimulation, not whether the hypothalamus or pituitary is normal. A recently acquired central defect may produce a seemingly adequate response before sustained ACTH deficiency causes adrenal atrophy. Historic peak cortisol cutoffs cannot be universally applied to newer assays. Therefore, a reassuring stimulation result does not automatically exclude acute central insufficiency when the clinical story and paired ACTH/cortisol results strongly suggest it.

In glucocorticoid-induced adrenal insufficiency, the 2024 joint guideline recommends morning cortisol as a first test when assessing HPA recovery during taper: >10 µg/dL suggests recovery, 5–10 µg/dL requires continued physiologic replacement and later reassessment, and <5 µg/dL suggests continued replacement with reassessment. These recovery thresholds are NOT interchangeable with cosyntropin-stimulated assay cutoffs used to diagnose primary insufficiency (Beuschlein et al., 2024).

Autoimmune clues and differential: A patient with type 1 diabetes, autoimmune thyroid disease, vitiligo, or a family history of autoimmune disease may have polyglandular autoimmunity. In a critically ill patient with acute hemorrhage or sepsis, bilateral adrenal hemorrhage is a separate consideration. Severe hyperkalemia, a rising creatinine, and hypotension may coexist with multiple processes, so finding one potential precipitant does not eliminate adrenal crisis.

Management Principles

In suspected adrenal crisis, obtain cortisol and ACTH first ONLY if sampling does not delay treatment, then administer parenteral hydrocortisone, isotonic fluids, and indicated glucose/electrolyte therapy immediately while treating the trigger. Diagnostic cosyntropin testing should follow after stabilization when appropriate. Chronic exogenous glucocorticoid exposure is a common cause of HPA suppression; abrupt discontinuation is unsafe, and patients with current or recent exposure may require stress coverage during illness or procedures (Beuschlein et al., 2024; Bornstein et al., 2016).

Physiologic versus stress replacement: Maintenance glucocorticoid replacement imitates basal cortisol needs; intercurrent fever, trauma, vomiting, or surgery can rapidly exceed physiologic coverage. Primary disease also requires mineralocorticoid assessment and often fludrocortisone replacement. Patients need specific sick-day instructions, medical alert identification, emergency injectable therapy access, and clear emergency follow-up (Bornstein et al., 2016).

Clinical Reasoning Priorities

Clinical fork: A patient with type 1 diabetes has progressive nausea, hypotension, oral pigmentation, sodium 130 mmol/L, potassium 6.5 mmol/L, low morning cortisol, and elevated ACTH. Cortical failure with aldosterone deficiency explains the combined sodium, potassium, and pigmentation pattern. A second patient abruptly stops prolonged glucocorticoids and develops hypotension and low cortisol without hyperpigmentation or marked hyperkalemia; central suppression is more likely because renin–angiotensin control of aldosterone often remains intact. Both can develop life-threatening crisis and require treatment before full etiologic localization.

High-Yield Distinctions

  • Addison disease commonly denotes chronic primary adrenal insufficiency; “adrenal insufficiency” also includes central disorders.
  • Hyperkalemia favors mineralocorticoid deficiency, but normal potassium does not rule out crisis.
  • A cosyntropin peak cortisol cutoff must be assay-specific; do not transplant historic thresholds into a current protocol.

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References

Beuschlein, F., Else, T., Bancos, I., Hahner, S., Hamidi, O., van Hulsteijn, L., Husebye, E. S., Karavitaki, N., Prete, A., Vaidya, A., Yedinak, C., & Dekkers, O. M. (2024). European Society of Endocrinology and Endocrine Society joint clinical guideline: Diagnosis and therapy of glucocorticoid-induced adrenal insufficiency. Journal of Clinical Endocrinology & Metabolism, 109(7), 1657–1683. https://doi.org/10.1210/clinem/dgae250

Bornstein, S. R., Allolio, B., Arlt, W., Barthel, A., Don-Wauchope, A., Hammer, G. D., Husebye, E. S., Merke, D. P., Murad, M. H., Stratakis, C. A., & Torpy, D. J. (2016). Diagnosis and treatment of primary adrenal insufficiency: An Endocrine Society clinical practice guideline. Journal of Clinical Endocrinology & Metabolism, 101(2), 364–389. https://doi.org/10.1210/jc.2015-1710

Else, T., & Hammer, G. D. (2019). Disorders of the adrenal cortex. In G. D. Hammer & S. J. McPhee (Eds.), Pathophysiology of disease: An introduction to clinical medicine (8th ed., Chapter 21). McGraw-Hill Education.

Penman, I. D., Ralston, S. H., Strachan, M. W. J., & Hobson, R. P. (Eds.). (2023). Davidson’s principles and practice of medicine (24th ed.). Elsevier.

Polomoff, C. M., Chen, J. T., & Dang, D. K. (2026). Adrenal gland disorders. In M. A. Chisholm-Burns, J. M. Kolesar, P. M. Malone, K. C. Lee, B. P. Bookstaver, & K. R. Matthias (Eds.), Pharmacotherapy principles & practice (7th ed., Chapter 46). McGraw Hill.