What is the medical term for elevated lactic acid?

Medical Terms for Elevated Lactic Acid

The medical terms for elevated lactic acid are hyperlactatemia and lactic acidosis, with the latter specifically referring to elevated lactic acid levels accompanied by a decrease in blood pH below 7.35. 1

Definitions and Distinction

• Hyperlactatemia: Elevated blood lactate concentration without accompanying acidosis
• Lactic acidosis: Elevated blood lactate concentration with serum pH < 7.35 2

Classification

Lactic acidosis is traditionally classified into two main types:

Type A Lactic Acidosis

• Associated with tissue hypoperfusion or hypoxia
• Common causes:
  • Cardiogenic shock
  • Septic shock
  • Hypovolemic shock
  • Trauma
  • Severe hypoxemia 3

Type B Lactic Acidosis

• Occurs without evidence of tissue hypoperfusion or shock
• Causes include:
  • Seizures
  • Liver failure
  • Hematologic malignancies
  • Congenital enzyme deficiencies
  • Thiamine deficiencies
  • Diabetes mellitus (particularly during ketoacidosis)
  • Alcohol abuse
  • Medication-induced 3, 4

Diagnostic Thresholds

When interpreting serum lactate levels:

• 2–5 mmol/L: Considered elevated and should be correlated with clinical symptoms

• 5 mmol/L: Abnormal

• 10 mmol/L: Indicates serious and potentially life-threatening conditions 1

Clinical Significance

Elevated lactate levels have important implications:

1. Prognostic value: In acute mesenteric ischemia, elevated serum lactate levels >2 mmol/L are associated with irreversible intestinal ischemia (Hazard Ratio: 4.1) 1, 5

2. Diagnostic utility: Elevated lactate combined with specific symptoms can guide diagnosis:

   • In abdominal pain, elevated lactate may indicate mesenteric ischemia 5
   • In HIV patients on antiretroviral therapy, elevated lactate may signal NRTI-induced mitochondrial toxicity 1

3. Monitoring parameter: During exercise testing, lactate threshold (anaerobic threshold) marks the point at which lactate accumulation increases rapidly, occurring at approximately 50-60% of predicted VO₂max in sedentary individuals 1

Important Considerations in Measurement

Accurate lactate measurement requires:

• Prechilled fluoride-oxalate tubes
• Immediate transport on ice to laboratory
• Processing within 4 hours of collection
• Blood collection without tourniquet, fist-clenching, or stasis 1

Pitfalls to Avoid

1. Assuming all elevated lactate is due to tissue hypoxia: Many cases of lactic acidosis, especially Type B, occur without tissue hypoperfusion 2, 6

2. Overlooking medication-induced causes: Numerous medications can cause hyperlactatemia or lactic acidosis, including epinephrine, albuterol, and certain antiretrovirals 4

3. Dismissing mild elevations: Even mild elevations (2-5 mmol/L) can be clinically significant when correlated with symptoms 1

4. Relying solely on lactate levels: Interpretation should include assessment of acid-base status, anion gap, and clinical context 6

Remember that elevated lactate levels should prompt thorough investigation of the underlying cause, as appropriate management depends on correctly identifying the etiology.