Hyperreninemic hypoaldosteronism in the critically ill: a new entity

Area of Science:

• Endocrinology
• Critical Care Medicine
• Nephrology

Background:

• Adrenal gland function is crucial in critical illness.
• Persistent hypotension is a common complication in intensive care units.
• The role of adrenal hormones in critical illness-related hypotension requires further clarification.

Purpose of the Study:

• To investigate adrenal gland function in critically ill patients with persistent hypotension.
• To identify potential causes of hypoaldosteronism in this patient population.

Main Methods:

• Evaluated 28 severely ill patients with persistent hypotension.
• Measured plasma cortisol, plasma renin activity (PRA), and plasma aldosterone concentration.
• Assessed aldosterone response to ACTH and angiotensin II infusions.
• Investigated potential contributing factors like infection, dopamine, and angiotensin-converting enzyme activity.

Main Results:

• Patients exhibited increased plasma cortisol and elevated PRA.
• A significant subset (18/28) showed inappropriately low plasma aldosterone levels.
• Aldosterone levels were low despite normal serum potassium and increased 18-hydroxycorticosterone.
• Only 2 of 14 patients showed a normal aldosterone response to ACTH or angiotensin II.
• Hypotension was associated with major infections and a high mortality rate (78%) in patients with low aldosterone.

Conclusions:

• Selective hypoaldosteronism, characterized by low aldosterone with high renin, is present in a substantial percentage of hypotensive critically ill patients.
• The defect appears localized to the zona glomerulosa cells of the adrenal cortex.
• Infection is a common underlying condition, but other factors do not fully explain the observed hypoaldosteronism.