Normal Anion-Gap Acidosis (NAGMA) - Differential Diagnosis Framework and Workup NAGMA - Chem, ABG or VBG - Calculate Anion Gap - UAG and Urine osmolar gap - UA with urine pH Calculate Urinary Anion Gap - Estimate urine ammonium concentration if increased or decreased in hyperchloremia - GI • Urine osmolar gap > 400 • (+) NH4 in the urine - Renal • Urine osmolar gap < 150 • (-) NH4 in the urine 1. Chloride Intoxication - Normal saline infusion - Hyperalimentation 2. Renal Loss of HCO3 - Renal insufficiency (GFR 20-50 ml/min) - Acetazolamide therapy - Hypoaldosteronism - Renal Tubular Acidosis (RTA): Type 1: Distal RTA: • Impaired H+ secretion • Urine pH > 5.5 • Serum K low/normal Type 2: Proximal RTA: • Low HCO3 absorption • Urine pH < 5.5 • Serum K: low/normal Type 4: Hyperkalemic RTA: • Urine pH > 5.5 • Serum K high/normal 3. GI Loss of HCO3 - Diarrhea - High output fistulas - Pancreatic/Biliary drainage - Ureteroileostomy/ureterosigmoidostomy - Surgical drains - Chronic laxative abuse - Villous adenoma - Losses via NGT tube By Dr. Ravi Singh @rav7ks #Normal #NonAnionGap #Acidosis #Metabolic #NAGMA #Differential #Diagnosis #Workup #nephrology
