American Association of Critical-Care Nurses (AACN) Certification Practice Test

What result is indicated by a lactate level greater than 4 mmol/L?

1. Normal condition

2. Hyperlactatemia

3. Lactic acidosis

4. Dehydration

The correct answer is: Lactic acidosis

A lactate level greater than 4 mmol/L typically indicates lactic acidosis, which is a condition characterized by an excess of lactic acid in the bloodstream. Lactic acid is produced when the body undergoes anaerobic metabolism, often due to inadequate oxygenation of tissues, which can occur in various clinical scenarios, including sepsis, shock, or significant hypoperfusion. When the lactate level rises above 4 mmol/L, it suggests that the body’s equilibrium is disrupted, and the accumulation of lactate could be indicative of a more severe metabolic derangement. This elevation serves as a marker for tissue hypoxia and can be critical in determining the severity of a patient’s condition. In clinical practice, the interpretation of high lactate levels is essential for guiding interventions, such as fluid resuscitation, vasopressor therapy, or addressing the underlying cause of tissue hypoperfusion. Identifying lactic acidosis allows healthcare providers to take prompt actions to improve oxygen delivery and restore acid-base balance, which is vital in critical care settings.