Is an elevated lactic acid level a requirement for a diagnosis of sepsis (Systemic Inflammatory Response Syndrome)?

From the Guidelines

No, an elevated lactic acid level is not a requirement for a diagnosis of sepsis. While lactic acid elevation (typically >2 mmol/L) is one criterion used in identifying sepsis, it is not mandatory for diagnosis. Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. The current clinical criteria for sepsis (Sepsis-3) focus on the Sequential Organ Failure Assessment (SOFA) score or the quick SOFA (qSOFA) criteria, which include altered mental status, systolic blood pressure ≤100 mmHg, and respiratory rate ≥22 breaths per minute. Lactic acid is an important biomarker that reflects tissue hypoperfusion and cellular stress during sepsis, and its elevation correlates with increased mortality risk. However, some patients with sepsis may have normal lactate levels, particularly early in the disease course or in cases where compensatory mechanisms are still effective. Clinicians should evaluate the complete clinical picture, including vital signs, organ function assessments, and other laboratory values, rather than relying solely on lactate levels when diagnosing sepsis 1.

Some key points to consider when diagnosing sepsis include:

• The SOFA score or qSOFA criteria should be used to identify patients with sepsis 1
• Lactic acid levels can be used as a marker of tissue hypoperfusion, but are not required for diagnosis 1
• Clinicians should evaluate the complete clinical picture, including vital signs, organ function assessments, and other laboratory values, when diagnosing sepsis 1
• Early identification and treatment of sepsis are critical to improving outcomes 1

It's worth noting that the Surviving Sepsis Campaign guidelines suggest that lactate levels can be used to guide resuscitation in patients with septic shock, but are not a requirement for diagnosis 1. Overall, the diagnosis of sepsis should be based on a combination of clinical criteria, laboratory values, and organ function assessments, rather than relying solely on lactic acid levels.

From the Research

Diagnosis of Sepsis

• The diagnosis of sepsis is complex and multifaceted, and elevated lactic acid levels are not a requirement for diagnosis 2, 3, 4.
• While lactate levels are often used as a marker for sepsis, they are not specific to infection and can be elevated in other conditions 2.
• The use of lactate levels in sepsis diagnosis has been controversial, with some studies suggesting that it may lead to unnecessary broad-spectrum antibiotic use and fluid overload 2.

Lactate Levels and Sepsis Severity

• Elevated lactate levels have been associated with increased mortality and poor outcomes in sepsis patients 3, 5, 6.
• However, a normal lactate level does not rule out sepsis, and patients with normal lactate levels but abnormal bicarbonate or anion gaps may still be at risk for adverse outcomes 4.
• The sensitivity and specificity of lactate levels for predicting sepsis and deterioration vary depending on the threshold used and the patient population 3, 6.

Clinical Implications

• The use of lactate levels in sepsis diagnosis and management should be considered in the context of other clinical factors and laboratory results 2, 3, 4.
• Early recognition and treatment of sepsis are critical, and lactate levels can be a useful tool in identifying patients at risk for deterioration 5, 6.
• However, lactate levels should not be relied upon as the sole criterion for diagnosis or management, and a comprehensive approach to sepsis care is necessary 2, 3, 4.