Critical Care Medicine-Endocrine Disorders>>>>>Hypothalamic-Pituitary-Adrenal Axis
Question 2#

A 76-year-old man with COPD, and prior head and neck radiation for a pituitary tumor, and worsening dementia presents with hypotension after running out of his medications last week. He is admitted to the ICU for management of hypotension.

Which of the following electrolyte values are most likely present?

A. Na 129 mEq/L; K 5.4 mEq/L; HCO3 18 mEq/L; BUN 30 mg/dL; Glucose 84 mg/dL
B. Na 129 mEq/L; K 3.9 mEq/L; HCO3 20 mEq/L; BUN 12 mg/dL; Glucose 84 mg/dL
C. Na 140 mEq/L; K 2.7 mEq/L; HCO3 28 mEq/L; BUN 30 mg/dL; Glucose 180 mg/dL
D. Na 145 mEq/L; K 4.3 mEq/L; HCO3 24 mEq/L; BUN 12 mg/dL; Glucose 140 mg/dL

Correct Answer is B


Correct Answer: B

This patient likely has secondary adrenal insufficiency from radiation affecting the pituitary gland, resulting in a deficit in ACTH production. Other potential causes of secondary insufficiency include pituitary tumors or craniopharyngiomas, postpartum hypopituitarism (“Sheehan’s syndrome”), and pituitary infiltrative diseased (hemochromatosis, sarcoidosis). There may be clinical manifestations of a pituitary or hypothalamic tumor, such as symptoms and signs of deficiency of other anterior pituitary hormones, headache, or visual field defects. This patient has developed adrenal crisis because he has been unable to take his daily replacement steroids. When differentiating primary from secondary adrenal insufficiency, it is important to remember that mineralocorticoid production is affected in primary but unchanged in secondary adrenal insufficiency (ACTH does not play a major role in regulation of aldosterone). Thus, hyperkalemia is usually present in primary insufficiency but absent in secondary. Hyponatremia is a feature of both, but in primary insufficiency it is associated with volume contraction resulting in an elevated blood urea nitrogen (BUN) and creatinine; whereas in secondary adrenal insufficiency, hyponatremia is dilutional because of decreased ability to excrete water and increased vasopressin levels. Hypoglycemia is present in both primary and secondary because of cortisol deficiency. Hyperaldosteronism is characterized by a normal sodium, hypokalemia, alkalemia, and hyperglycemia. 



  1. Vincent JL, Abraham E, Moore FA, et al, eds. Textbook of Critical Care. 7th ed. Philadelphia, PA: Elsevier; 2017.