II. Types

  1. Elevated Anion Gap Metabolic Acidosis
  2. Hyperchloremic Metabolic Acidosis (normal Anion Gap)
    1. See Hyperchloremia

III. Causes: Metabolic Acidosis and Elevated Anion Gap (Mnemonic: "MUD PILERS")

  1. Methanol, Metformin
  2. Uremia
  3. Diabetic Ketoacidosis (DKA), Alcoholic ketoacidosis or starvation ketosis
  4. Paraldehyde, Phenformin (neither used in U.S. now)
    1. Propofol Infusion Syndrome has been proposed as a replacement in mnemonic
  5. Iron, Isopropyl Alcohol, and Isoniazid (due to Seizures)
  6. Lactic Acidosis
  7. Ethylene Glycol, Ethyl Alcohol
  8. Rhabdomyolysis
  9. Salicylates (do not miss Chronic Salicylate Poisoning)
  10. Other Causes
    1. Hyperalbuminemia
    2. Administered anions

IV. Causes: Metabolic Acidosis and Normal Anion Gap (Hyperchloremia)

  1. Hypokalemia with Metabolic Acidosis
    1. Diarrhea
    2. Ureteral diversion
      1. Uretero-sigmoidostomy
      2. Ileal Bladder
      3. Ileal ureter
    3. Renal Tubular Acidosis (proximal or distal)
    4. Mineralocorticoid Deficiency
      1. Angiotensin Deficiency: Liver Failure
      2. ACE Inhibitor
      3. Renin Deficiency
        1. Aging
        2. Extracellular fluid volume expansion
        3. Lead
        4. Beta Blockers
        5. Prostaglandin Inhibitor
        6. Methyldopa
    5. Carbonic anhydrase inhibitor
      1. Acetazolamide
      2. Mefenamic acid
    6. Post-hypocapnia
  2. Hyperkalemia (or normal potassium) Metabolic Acidosis
    1. Renal Failure (Early)
    2. Renal Disease
      1. SLE Interstitial Nephritis
      2. Amyloidosis
      3. Hydronephrosis
      4. Sickle Cell Nephropathy
    3. Acidifying agents
      1. Ammonium Chloride
      2. Calcium Chloride
      3. Arginine
    4. Sulfur toxicity

V. Causes: Metabolic Acidosis and Elevated Osmolal Gap

  1. Toxic Alcohol ingestion
    1. Eythylene glycol
    2. Methanol
  2. Serum Ketone increase (ketosis)
    1. Alcoholic ketoacidosis
    2. Diabetic Ketoacidosis

VI. Labs

  1. Arterial Blood Gas
    1. Arterial pH decreased
    2. Serum bicarbonate decreased
    3. PaCO2 decreased
      1. PaCO2 drops 1.2 mmHg per 1 meq/L bicarbonate fall
      2. Calculated PaCO2 = 1.5 x HCO3 + 8 (+/- 2)
        1. Useful in High Anion Gap Metabolic Acidosis
        2. Measured PaCO2 discrepancy: respiratory disorder
  2. Serum Chemistry panel
    1. Anion Gap
      1. Increased in high Anion Gap Metabolic Acidosis
    2. Excess Anion Gap <23 mEq/L
      1. Suggests Non-Anion Gap Metabolic Acidosis
    3. Serum Potassium
      1. Investigate normal Anion Gap Metabolic Acidosis
      2. See above
    4. Serum Chloride
      1. Elevated in normal Anion Gap Metabolic Acidosis
    5. Serum bicarbonate
      1. Decreased in increased Anion Gap Metabolic Acidosis
      2. Bicarbonate decrease matches Anion Gap increase
  3. Urinalysis with Urine pH
    1. Urine pH >6: Suggests Renal cause
    2. Urine pH <6: Suggests Gastrointestinal cause
  4. Urine Anion Gap (obtain urine electrolytes)
    1. Decreased Urine Anion Gap <-10
      1. Extrarenal Non-Anion Gap Metabolic Acidosis
    2. Increased Urine Anion Gap >+10
      1. Renal Non-Anion Gap Metabolic Acidosis

VII. Labs: Consider in Metabolic Acidosis with Increased Anion Gap

  1. Basic chemistry panel as above (Serum Glucose, Blood Urea Nitrogen)
  2. Serum Lactate
  3. Serum Ketones (or Beta hydroxybutyrate)
  4. Salicylate Level
  5. Blood Alcohol level
  6. Ethylene Glycol level
  7. Creatinine Phosphokinase (CPK)
  8. Iron level
  9. Serum Albumin

VIII. References

  1. Arieff (1993) J Crit Illn 8(2): 224-46 [PubMed] (or open in [QxMD Read])
  2. Narins (1982) Am J Med 72:496 [PubMed] (or open in [QxMD Read])
  3. Narins (1980) Medicine 59:161-95 [PubMed] (or open in [QxMD Read])
  4. Ghosh (2000) Fed Pract p. 23-33
  5. Rutecki (Dec 1997) Consultant, p. 3067-74
  6. Rutecki (Jan 1998) Consultant, p. 131-42

Images: Related links to external sites (from Google)

Ontology: Metabolic acidosis (C0220981)

Definition (NCI) Increased acidity in the blood secondary to acid base imbalance. Causes include diabetes, kidney failure and shock.
Definition (NCI) A condition in which the blood is too acidic. It may be caused by severe illness or sepsis (bacteria in the bloodstream).
Concepts Pathologic Function (T046)
MSH D000138
ICD10 E87.2
SnomedCT 59455009
English ACIDOSIS METABOLIC, Acidosis, metabolic, METABOLIC ACIDOSIS, Metabolic acidosis, NOS, metabolic acidosis, metabolic acidosis (diagnosis), Acidosis metabolic, Metabolic acidosis NOS, Metabolic Acidoses, Acidosis, Metabolic, Acidoses, Metabolic, Metabolic Acidosis, acidosis metabolic, acidosis metabolics, acidosys metabolic, metabolic acidosis disorder, Metabolic acidosis (disorder), acidosis; metabolic, metabolic; acidosis, Metabolic acidosis
Italian Acidosi metabolica, Acidosi metabolica NAS
Dutch metabole acidose NAO, acidose; metabool, metabool; acidose, metabole acidose
French Acidose métabolique SAI, ACIDOSE METABOLIQUE, Acidose métabolique
German metabolische Azidose NNB, AZIDOSE METABOLISCH, metabolische Azidose
Portuguese Acidose metabólica NE, ACIDOSE METABOLICA, Acidose metabólica
Spanish Acidosis metabólica NEOM, ACIDOSIS METABOLICA, acidosis metabólica (trastorno), acidosis metabólica, Acidosis metabólica
Japanese 代謝性アシドーシス, 代謝性アシドーシスNOS, タイシャセイアシドーシスNOS, タイシャセイアシドーシス
Czech Metabolická acidóza, Metabolická acidóza NOS
Hungarian Metabolicus acidosis, Metabolikus acidosis, Metabolikus acidosis k.m.n.

Ontology: Metabolic acidosis, normal anion gap (NAG) (C0268033)

Concepts Disease or Syndrome (T047)
SnomedCT 111377009
English Metabolic acidosis, normal anion gap (NAG), NOS, Metabolic acidosis, normal anion gap (NAG) (disorder), Metabolic acidosis, normal anion gap (NAG)
Spanish acidosis metabólica, hiato aniónico normal, acidosis metabólica, brecha aniónica normal (trastorno), acidosis metabólica, brecha aniónica normal, acidosis metabólica, hiato aniónico normal (trastorno), acidosis metabólica, anión gap normal, acidosis metabólica, desequilibrio aniónico normal

Ontology: Metabolic acidosis, increased anion gap (IAG) (C0268036)

Concepts Disease or Syndrome (T047)
SnomedCT 25998009
English Metabolic acidosis, increased anion gap (IAG), NOS, Metabolic acidosis, increased anion gap (IAG) (disorder), Metabolic acidosis, increased anion gap (IAG)
Spanish acidosis metabólica, hiato aniónico aumentado (trastorno), acidosis metabólica, hiato aniónico aumentado, acidosis metabólica con anión gap aumentado, acidosis metabólica, brecha aniónica aumentada, acidosis metabólica, brecha aniónica aumentada (trastorno), acidosis metabólica, desequilibrio aniónico aumentado