A Rare Endocrine Emergency in Pregnancy: A Case of Lymphocytic Hypophysitis Mimicking Adrenal Crisis Diagnosed Without Pituitary Imaging

Abstract

Lymphocytic hypophysitis (LH) is a rare autoimmune inflammation of the pituitary gland, typically presenting during late pregnancy or postpartum. It can lead to life-threatening hypopituitarism, but diagnosis is often delayed, especially in settings where MRI and endocrine labs are limited. A 29-year-old primigravida at 34 weeks presented with fatigue, postural hypotension, nausea, and hyponatremia. Initial evaluation suggested adrenal insufficiency. Laboratory studies revealed low morning cortisol, undetectable ACTH, and suppressed TSH and free T4, indicating central adrenal and thyroid insufficiency. Due to limited imaging availability, diagnosis was established clinically and biochemically as lymphocytic hypophysitis. Treatment with hydrocortisone and levothyroxine led to full symptomatic resolution and a healthy term delivery. This case highlights the need for clinical vigilance and early hormone replacement therapy in pregnant patients presenting with unexplained hypotension and electrolyte abnormalities, even in the absence of imaging. Lymphocytic hypophysitis should be a key differential diagnosis in late pregnancy endocrine crises.