Lactate

Lactate is the deprotonated form of lactic acid produced when cells convert pyruvate to lactate via lactate dehydrogenase, often during low-oxygen or high-intensity exercise. It serves as a fuel source for heart and brain, a shuttle between tissues, and a marker of tissue oxygenation and metabolic stress; elevated blood lactate can indicate hypoxia, sepsis, or intense exertion.

Lactate is a metabolic byproduct formed when cells use anaerobic respiration, common during intense exercise or low oxygen. Blood lactate levels help assess tissue oxygenation, metabolic stress or sepsis; values above about 4 mmol/L suggest lactic acidosis. Normal resting lactate is roughly 0.5–2 mmol/L and is similar in girls and boys. Elevated levels require medical evaluation.

High lactate indicates increased anaerobic metabolism—tissues aren’t getting enough oxygen or clearing lactate. It’s seen in shock, severe infection (sepsis), respiratory failure, cardiac arrest, intense exercise, liver dysfunction, seizures, certain drugs/toxins or mitochondrial disease. Elevated lactate suggests poor perfusion or metabolic stress and can lead to lactic acidosis; it requires prompt evaluation and treatment to address underlying causes.

Lactate acts as an important metabolic intermediate and signaling molecule. Produced by glycolysis, it regenerates NAD+ to sustain ATP production, shuttles between tissues (muscle to liver via the Cori cycle) for gluconeogenesis, and serves as a fuel for heart, brain, and oxidative muscle. Lactate also modulates cellular signaling, inflammation, and vascular responses, contributing to exercise adaptation and metabolic homeostasis.

Treatment of high lactate focuses on correcting the underlying cause and restoring tissue oxygenation and perfusion. Immediate measures include oxygen, intravenous fluids and, if needed, vasopressors or inotropes; treat shock or sepsis with appropriate antibiotics and source control. Address specific causes (stop offending drugs, dialysis for toxin/renal failure). Monitor lactate and acid–base status; bicarbonate is reserved for severe acidemia.

Lactation is triggered primarily by hormonal changes—rising prolactin for milk production and oxytocin for milk ejection—usually after pregnancy and birth. It can also occur from frequent nipple stimulation or breastfeeding, certain medications (e.g., antipsychotics, some antidepressants, domperidone), pituitary tumors (prolactinoma), hypothyroidism, chest surgery or trauma, and some herbal supplements that stimulate milk supply.