Lactate (lactic acid)
Also called: Lactate, Lactic acid
Lactate is a metabolic by-product that rises when oxygen delivery falls behind oxygen demand — a key sepsis, shock and ICU marker. Mildly raised by exercise, severely raised by tissue hypoperfusion.
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What does Lactate (lactic acid) measure?
Lactate is produced by glycolysis whenever a cell can't fully oxidise glucose to CO₂ and water — usually because oxygen delivery has fallen behind demand. Healthy resting lactate is <2 mmol/L; vigorous exercise transiently pushes it to 5–15 mmol/L. In hospital, lactate is one of the most-used real-time markers of severity in sepsis, septic shock, cardiogenic shock and major haemorrhage, because it rises before blood pressure drops and tracks tightly with mortality.
What does a high Lactate (lactic acid) level mean?
- Septic shock / severe sepsis — >4 mmol/L drives 'sepsis bundle' resuscitation.
- Cardiogenic shock, severe heart failure, post-cardiac arrest — global hypoperfusion.
- Massive haemorrhage — tissue oxygen delivery collapses.
- Hepatic failure — liver clears most circulating lactate.
- Metformin in renal failure — rare lactic acidosis.
- Mitochondrial disease, thiamine deficiency — impaired aerobic metabolism.
- Strenuous exercise — transient, normalises in <30 min.
What does a low Lactate (lactic acid) level mean?
- Generally favourable; clinically not pursued.
When to discuss with a doctor
Lactate is an inpatient / emergency marker, not a routine outpatient panel. A discharge report showing lactate >2 outside the setting of recent intense exercise warrants conversation with the discharging clinician. Above 4 in a non-exercising patient is an emergency. Mediora.AI flags the value with the sepsis threshold; do not self-interpret.