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