Which lab test is essential for identifying and monitoring sepsis?

Lactic acid (lactate) is essential for identifying and monitoring sepsis due to its role as a marker of tissue hypoperfusion and metabolic acidosis, which are critical components in the pathophysiology of sepsis. In a patient with sepsis, the body’s ability to adequately supply tissues with oxygen becomes compromised, leading to anaerobic metabolism and increased production of lactate. Elevated lactate levels indicate that the body is experiencing significant stress and can help assess the severity of the infection and the response to treatment.

While blood cultures are important for diagnosing the causative organism of the infection, and procalcitonin can be useful in distinguishing bacterial infections, lactate levels provide real-time information on the patient’s metabolic status, guiding immediate clinical decision-making. A complete blood count can offer insights into the patient's immune response, but it is not specific for sepsis. Therefore, lactic acid measurement is crucial in both the identification and ongoing assessment of patients with sepsis.