What can cause a false elevation in lactate levels?

From the Guidelines

False elevation in lactate levels can occur due to various factors, including elevated glycolate concentrations, which can falsely elevate plasma lactate concentration on some analyzers, as seen in ethylene glycol poisoning 1. When considering the potential causes of false elevated lactate levels, it's essential to take into account the context and underlying conditions of the patient.

• Medications and certain medical procedures can contribute to artificially raised lactate levels.
• Underlying medical conditions, such as liver disease, diabetic ketoacidosis, and thiamine deficiency, can also cause elevated readings without true tissue hypoxia.
• Physiological states like seizures, excessive muscle activity, and strenuous exercise can temporarily increase lactate production.
• Normal physiological states, such as pregnancy, can elevate baseline lactate levels. However, elevated glycolate concentrations, as observed in ethylene glycol poisoning, can be a significant cause of false elevation in lactate levels, as it can cross-react with some analyzers and produce falsely elevated lactate readings 1. To minimize false elevations, it's crucial to consider these factors and take appropriate measures, such as collecting blood samples without a tourniquet when possible, processing them immediately, and placing them on ice if analysis will be delayed.
• Understanding the specific analyzer's cross-reactivity is also vital in accurately interpreting lactate levels, especially in cases where ethylene glycol poisoning is suspected 1.
• The "lactate gap" has been suggested as a surrogate of glycolate, but its use requires knowledge of the specific analyzer's cross-reactivity, making it challenging to formalize into a recommendation 1.

From the FDA Drug Label

Metformin decreases liver uptake of lactate increasing lactate blood levels

• False elevation in lactate levels can be caused by:
  • Metformin, as it decreases liver uptake of lactate, increasing lactate blood levels 2
• This is a drug-related cause of elevated lactate levels.

From the Research

Causes of False Elevated Lactate

• Ethylene glycol intoxication can cause falsely elevated lactate measurements, as seen in a case report where a patient presented with severe metabolic acidosis and massive lactate elevation, which was later found to be due to ethylene glycol intoxication 3
• Certain medications, such as metformin, can cause lactic acidosis, which may be misinterpreted as a false elevation in lactate levels 4, 5
• Other medications, like venlafaxine, can also cause type B lactic acidosis, which is not secondary to tissue hypoperfusion or hypoxemia 6
• It is essential to confirm elevated lactate concentrations measured on intensive care unit and emergency department blood gas analysers with a clinical chemistry analyser in the main laboratory, especially in cases of suspected ethylene glycol intoxication or medication-related causes 3

Factors to Consider

• Tourniquet application for blood collection does not significantly increase lactate concentration, as shown in a study where there was no clinically significant increase in lactate concentration in the tourniquet compared to non-tourniquet arm in all groups, across all tourniquet application times, and over a range of lactate concentrations 7
• Clinicians should be aware of the many potential causes of lactate level elevation, as the clinical and prognostic importance of an elevated lactate level varies widely by disease state 4