Blood Lactic Acid

Aka: Blood Lactic Acid, Lactic Acidosis, Lactic Acidosis Definition, Lactic Acid

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II. Physiology

  1. See Glucose Metabolism

III. Causes: Tissue Hypoxia (Type A)

  1. Systemic hypoperfusion or shock
    1. Hypovolemia or Dehydration
    2. Cardiogenic Shock
    3. Septic Shock
    4. Seizure (transient)
  2. Local hypoperfusion
    1. Testicular Torsion
    2. Intestinal Volvulus
    3. Acute Mesenteric Ischemia
    4. Arterial embolism (e.g. Cerebrovascular Accident)
    5. Epinephrine infusion (causing tissue Hypoxia)
  3. Decreased arterial oxygen
    1. Hypoxemia (e.g. Asthma)
    2. Severe Anemia
    3. Carbon Monoxide Poisoning

IV. Causes: No tissue Hypoxia (Type B)

  1. Medical conditions (Type B1)
    1. Severe liver disease (related to Cori Cycle Lactic Acid generation)
    2. Cancer
    3. Thiamine deficiency
  2. Medications or toxins (Type B2, most are via mitochondrial cytopathy)
    1. Acetaminophen
    2. Cyanide
    3. Metformin
    4. Beta-2 Agonist (via increased pyruvate)
      1. Albuterol 10 mg neb increases Lactic Acid 0.8 mmoL/L
      2. Zitek (2016) Acad Emerg Med 23(6): 718-21 +PMID:26857949 [PubMed]
    5. Isoniazid (via liver toxicity)
    6. Tetracycline
    7. Linezolid
    8. Propofol
      1. Causes Propofol Infusion Syndrome
    9. Propylene gylcol (solvent for many Parenteral drugs)
      1. Nitroglycerin
      2. Lorazepam
      3. Etomidate
      4. Phenytoin
    10. Nucleoside Reverse Transcriptase Inhibitor (NRTI agents)
      1. Zidovudine
      2. Lamivudine
      3. Didanosine
      4. Stavudine
    11. Toxic Alcohol ingestion
      1. Ethylene Glycol Poisoning
      2. Methanol Poisoning
  3. Congenital metabolic conditions (Type B3)
    1. Mitochondrial disorders
    2. Hypoglycemia

V. Precations

  1. Lactic Acid is primarily used as a Sepsis marker and tissue ischemia marker (e.g. ischemic bowel)
    1. However, differential diagnosis of Lactic Acidosis is broad (see above)
    2. Avoid ordering Lactic Acid in low risk patients (non-toxic, previously healthy)
    3. Consider superimposed factors resulting in Lactic Acidosis (Asthma, Albuterol)
  2. Lactic Acid clearance outside Sepsis does not uniformly improve with Intravenous Fluids
    1. Cardiogenic Shock can also increase Lactic Acid and will worsen with excess fluids
    2. Outside Sepsis, Exercise caution in aggressive fluid Resuscitation to lower Lactic Acid
  3. References
    1. Herbert and Crager in Herbert (2018) EM:Rap 18(4): 1-3

VI. Efficacy: Children

  1. Lactic Acid has historically not been used in children, as much as it has become a mainstay in adult evaluation
  2. Lactic Acid may have more evidence for use in sick children (esp. Sepsis, Trauma) and their disposition
    1. Increased organ dysfunction in children with elevated Lactic Acid >4 mmol/L
      1. Scott (2012) Acad Emerg Med 19(11): 1276-80 +PMID: 23167859 [PubMed]
    2. Predicted need for Critical Care in children with Trauma and pre-hospital elevated Lactic Acid >4 mmol/L
      1. Shah (2013) Pediatr Emerg Care 29(6): 715-9 +PMID: 23714761 [PubMed]
    3. Predicted in-hospital mortality for critically ill children
      1. Bai (2014) BMC Pediatr 14:83 +PMID: 24673817 [PubMed]

VII. References

  1. (2013) Endo and Acid Base Disorders, EM Bootcamp, Las Vegas

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