fludrocortisone + furosemide

Fludrocortisone + furosemide is a combination of two pharmaceutical agents used primarily in diagnostic testing and occasionally in the management of certain renal and electrolyte disorders. Fludrocortisone is a synthetic mineralocorticoid that acts as an agonist at the mineralocorticoid receptor, increasing sodium reabsorption and potassium excretion in the distal tubules of the kidney. Furosemide is a loop diuretic that inhibits the Na+, K+, 2Cl- cotransporter (NKCC2) in the thick ascending limb of Henle’s loop, leading to increased excretion of sodium, chloride, and water. When administered together, this combination enhances distal tubular sodium delivery (via furosemide) while simultaneously stimulating direct sodium reabsorption and hydrogen ion secretion (via fludrocortisone), resulting in pronounced urinary acidification without causing systemic acidosis. This pharmacological synergy has been utilized as an alternative to oral acid loading tests for diagnosing renal tubular acidosis (RTA), especially when standard tests are contraindicated or poorly tolerated[1][3][4]. The combination may also be considered for managing metabolic acidosis associated with chronic renal insufficiency or hypoaldosteronism when monotherapy is insufficient[3]. However, concurrent use increases risk for hypokalemia and other electrolyte disturbances[2][5].

Other names

Furosemide-fludrocortisone loading test