SUN-455 - Contrasting Primary and Secondary Adrenal Insufficiency: Two Illustrative Cases

Background:
Adrenal insufficiency is a potentially life-threatening condition with heterogeneous presentations depending on whether the pathology is primary (adrenal) or secondary (central). We present two illustrative cases, one of autoimmune primary adrenal insufficiency and a rare case of secondary adrenal insufficiency related to neurosarcoidosis.
Case Presentations:
The first case is a 52-year-old woman with Hashimoto’s hypothyroidism and vitiligo who presented to the hospital with months of fatigue, weight loss, orthostatic symptoms, muscle cramps, and severe hyponatremia (Na 121 mmol/L) with hyperkalemia (K 5.2 mmol/L). On evaluation she was found to have significantly low cortisol (0.4 µg/dL), elevated ACTH (1097 pg/mL), absent response to cosyntropin stimulation, and positive 21-hydroxylase antibodies, confirming primary adrenal insufficiency due to autoimmune adrenalitis. She experienced partial improvement with hydrocortisone and marked symptomatic and biochemical improvement after initiation of fludrocortisone.
The second case is a 47-year-old woman with cutaneous sarcoidosis and progressive neurologic decline who developed severe postoperative hyperkalemia following craniotomy for leptomeningeal biopsy. She was found to have a low morning cortisol (0.4 µg/dL) with inappropriately low ACTH (6 pg/mL). Her clinical presentation included months of fatigue, cognitive slowing, dizziness, and weakness predating surgery. She demonstrated rapid clinical improvement with stress-dose hydrocortisone. Subsequent findings supported secondary adrenal insufficiency, likely related to central involvement from neurosarcoidosis.

Discussion:
These cases highlight classic distinctions between primary and secondary adrenal insufficiency. Primary insufficiency was characterized by autoimmune clustering, hyperpigmentation, hyponatremia, hyperkalemia, elevated ACTH, and a requirement for glucocorticoid and mineralocorticoid replacement. In contrast, secondary insufficiency presented with nonspecific systemic symptoms, low ACTH, preserved aldosterone physiology, and dramatic response to glucocorticoid replacement alone. Both cases illustrate the diagnostic challenges posed by overlapping symptoms and the importance of considering adrenal insufficiency in patients with unexplained electrolyte abnormalities, chronic fatigue, or autoimmune and inflammatory disease.

Conclusion:
Primary and secondary adrenal insufficiency can present insidiously and be unmasked during acute illness. Careful interpretation of cortisol, ACTH, electrolyte patterns, autoimmune markers, and clinical context is needed for accurate diagnosis and appropriate management. These contrasting cases emphasize the need for heightened clinical suspicion and tailored hormone replacement strategies to optimize outcomes.

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