Why order lactate (lactic acid) levels?

From the Guidelines

Lactate levels should be ordered to guide resuscitation in patients with septic shock, as elevated lactate levels are associated with worse outcomes and lactate-guided resuscitation has been shown to reduce mortality 1.

Importance of Lactate Levels

Lactate levels are a crucial marker of tissue hypoperfusion and can help diagnose conditions like lactic acidosis.

• Elevated lactate levels are associated with increased mortality and morbidity in patients with septic shock 1.
• Lactate-guided resuscitation has been shown to reduce mortality in patients with septic shock, with a significant reduction in mortality seen in lactate-guided resuscitation compared to resuscitation without lactate monitoring (RR 0.67; 95% CI, 0.53–0.84; low quality) 1.

Clinical Application

In clinical practice, lactate levels can be used to guide fluid resuscitation and vasopressor therapy in patients with septic shock.

• The Surviving Sepsis Campaign recommends guiding resuscitation to normalize lactate in patients with elevated lactate levels as a marker of tissue hypoperfusion (weak recommendation, low quality of evidence) 1.
• An initial target mean arterial pressure (MAP) of 65 mm Hg is recommended in patients with septic shock requiring vasopressors, and lactate levels can be used to guide further hemodynamic assessment and resuscitation 1.

Key Takeaways

• Lactate levels are an important marker of tissue hypoperfusion and can help guide resuscitation in patients with septic shock.
• Elevated lactate levels are associated with increased mortality and morbidity, and lactate-guided resuscitation has been shown to reduce mortality.
• Lactate levels should be ordered as part of the initial assessment and resuscitation of patients with septic shock, and used to guide further hemodynamic assessment and resuscitation.

From the FDA Drug Label

There have been postmarketing cases of metformin-associated lactic acidosis, including fatal cases. These cases had a subtle onset and were accompanied by nonspecific symptoms such as malaise, myalgias, abdominal pain, respiratory distress, or increased somnolence; however, hypotension and resistant bradyarrhythmias have occurred with severe acidosis Metformin associated lactic acidosis was characterized by elevated blood lactate concentrations (>5 mmol/L), anion gap acidosis (without evidence of ketonuria or ketonemia), and an increased lactate: pyruvate ratio; Metformin decreases liver uptake of lactate increasing lactate blood levels which may increase the risk of lactic acidosis, especially in patients at risk.

Lactate levels should be ordered to diagnose or rule out lactic acidosis, a potentially fatal condition associated with metformin use, especially in patients with risk factors such as renal impairment, age 65 or greater, or those taking certain concomitant medications 2.

• Key risk factors for metformin-associated lactic acidosis include:
  • Renal impairment
  • Age 65 or greater
  • Concomitant use of certain medications
  • Hepatic impairment
  • Excessive alcohol intake
• Clinical signs of lactic acidosis may be nonspecific, making laboratory diagnosis crucial.

From the Research

Reasons for Ordering Lactate Levels

• Lactate levels are commonly evaluated in acutely ill patients to assess the severity of their condition and to guide treatment decisions 3, 4
• Elevated lactate levels can be caused by various factors, including tissue hypoperfusion, sepsis, cardiac arrest, trauma, and medication-related causes 3, 5
• Lactate levels can be used as a diagnostic and prognostic tool to monitor the effectiveness of treatment and to predict patient outcomes 4, 6
• The measurement of lactate levels can help clinicians to identify patients with lactic acidosis, a condition characterized by an increase in blood lactate concentration and metabolic acidosis 7

Clinical Significance of Lactate Levels

• Elevated lactate levels are associated with poor clinical outcomes, including increased mortality and longer hospital stays 4, 6
• Lactate levels can be used to monitor the severity of metabolic acidosis and to guide treatment decisions, such as the use of sodium bicarbonate or other buffering agents 5, 7
• The classification of lactic acidosis into different types, such as type A (with evidence of tissue hypoxemia) and type B (without evidence of tissue hypoxemia), can help clinicians to tailor treatment to the underlying cause of the condition 7

Treatment of Lactic Acidosis

• The treatment of lactic acidosis typically involves the administration of sodium bicarbonate and the restoration of adequate tissue perfusion 4, 7
• Hemodialysis may be helpful in controlling sodium excess and removing certain medications that can cause lactic acidosis 7
• The effectiveness of other treatments, such as methylene blue, glucose, and insulin, is not yet established 7