Anion Gap

Calculates the anion gap to check for metabolic acidosis.

Na
Cl
HCO3
Anion Gap
Delta Gap
Delta Ratio

Anion Gap = Na - (Cl + HCO3-) Delta Gap = Anion Gap - 12 (nl anion gap)

Anion Gap Metabolic Acidosis: MUDPILERS

  • Methanol
  • Uremia
  • DKA/Alcoholic KA
  • Paraldehyde
  • Isoniazid
  • Lactic Acidosis
  • Etoh/Ethylene Glycol
  • Rhabdo/Renal Failure
  • Salicylates

Non-Anion Gap Acidosis: HARDUPS

  • Hyperalimentation
  • Acetazolamide
  • Renal Tubular Acidosis
  • Diarrhea
  • Uretero-Pelvic Shunt
  • Post-Hypocapnia
  • Spironolactone

Acute Respiratory Acidosis (Chronic Respiratory Acidosis = COPD/restrictive lung dz): any hypoventilation state

  • CNS Depression (drugs/CVA)
  • Airway Obstruction
  • Pneumonia
  • Pulmonary Edema
  • Hemo/Pneumothorax
  • Myopathy

Metabolic Alkalosis: CLEVER PD

  • Contraction
  • Licorice
  • Endo: (Conn's, Cushings, Bartter's)
  • Vomiting
  • Excess Alkali
  • Refeeding Alkalosis

Respiratory Alkalosis: CHAMPS (think speed up breathing)

  • CNS disease
  • Hypoxia
  • Anxiety
  • Mech Ventilators
  • Progesterone
  • Salicylates/Sepsis
Delta Ratio... Suggests...
< 0.4 Hyperchloremic normal anion gap acidosis
< 1 High AG & normal AG acidosis
1 to 2 Pure Anion Gap Acidosis
Lactic acidosis: average value 1.6
DKA more likely to have a ratio closer to 1 due to urine ketone loss
> 2 High AG acidosis and a concurrent metabolic alkalosis or a pre-existing compensated respiratory acidosis








The NNT : Quick Summaries of Evidence-Based Medicine