How does lactate serve as a marker in sepsis, and which factors can raise lactate independently of tissue hypoperfusion?

• A. Elevated lactate correlates with severity; beta-agonists, liver dysfunction, alcohol, and metformin can raise lactate independently of hypoxia
• B. Lactate decreases with sepsis
• C. Lactate has no prognostic value in sepsis
• D. Only tissue hypoperfusion raises lactate

Answer: (A)

Lactate rises in sepsis as a sign of metabolic stress and the body's impaired ability to meet energy demands. While tissue hypoperfusion and anaerobic metabolism certainly raise lactate, production and clearance are also influenced by other factors, so lactate can be elevated even when perfusion is not severely reduced. Beta-adrenergic stimulation from medications or stress increases glycolysis and lactate production; liver dysfunction impairs the main route of lactate clearance; alcohol use shifts the cellular redox state toward lactate production; and metformin—especially with reduced kidney function—can disrupt hepatic lactate clearance and promote lactic acidosis. Because of these multiple pathways, higher lactate levels correlate with greater illness severity and worse prognosis, and serial lactate measurements help track response to treatment. The other statements misstate lactate’s role in sepsis: lactate does not always decrease, it can have prognostic value, and it is not solely governed by tissue hypoperfusion.