Lactate

Background

• Byproduct of anaerobic metabolism
• Serum lactate is a marker of tissue hypoperfusion and metabolic stress

Normal Values

• Normal: 0.5-2.0 mmol/L
• Elevated (hyperlactatemia): 2.0-4.0 mmol/L
• Severely elevated: >4 mmol/L

Interpretation

• Elevated lactate in the ED most commonly indicates tissue hypoperfusion (sepsis, shock, cardiac arrest)
• Lactate clearance (>10% decrease over 2-6 hours) is associated with improved outcomes in sepsis
• Type A (hypoxic): shock, cardiac arrest, mesenteric ischemia, severe hypoxemia, seizures, strenuous exercise
• Type B (non-hypoxic): medications (metformin, epinephrine, albuterol), liver failure, thiamine deficiency, malignancy, DKA
• Lactate >4 mmol/L in sepsis confers high mortality and qualifies as septic shock by Sepsis-3 criteria

See Also

• Lactic acidosis
• Sepsis
• Shock
• Anion gap
• BMP