Causes of Metabolic Alkalosis: Differential Diagnosis ECF volume contracted: urine chloride concentration <20 meq/L • Gastric alkalosis: vomiting/ nasogastric suction • Chloride-rich diarrhea (congenital chloridorrhea) • Status/ postchronic hypercapnia (acute reversal of chronic respiratory acidosis) • Cystic fibrosis with major sweating • Thiazide or loop diuretics after renal tubule diuretic effect has dissipated • Some villous adenomas ECF volume expanded: urine chloride concentration > 20 meq/L • Primary hyperaldosteronism (unilateral adenoma/ bilateral hyperplasia/ glucocorticoid-sensitive hyperaldosteronism) • Severe Cushing syndrome (especially because of ectopic ACTH) • Exogenous mineralocorticoids • Reduced 11-ß (OH) steroid dehydrogenase activity: Chronic licorice/carbenoxolone ingestion, Congenital AME syndrome (11-ß HSD type 2 inactivating mutation) • Renin-secreting tumors • Some forms of congenital adrenal hyperplasia: 11-ß hydroxylase deficiency, 17-a hydroxylase deficiency • Liddle syndrome ECF volume contracted: but urine chloride concentration > 20 meq/L (generally indicates a renal tubule reabsorptive defect) • Thiazide or loop diuretics actively working • Bartter syndrome (defective Na reabsorption in loop of Henle, furosemide-like lesion) • Gitelman syndrome (defective Na reabsorption at the thiazide-sensitive site) Metabolic alkalosis: other • Severe potassium deficiency • Milk (calcium) alkali syndrome • NaHCO3 loads with markedly reduced GFR • Refeeding after fasting #Metabolic #Alkalosis #Differential #Diagnosis #Causes #nephrology
