16/09/2025
■■Ddx of ⬆️ lactate
🧠 Understanding Lactate:
■Overview:
Lactate, a product of anaerobic glycolysis, serves as a crucial indicator of either Type A (oxygen delivery issues) or Type B (altered metabolism) causes. It’s predominantly cleared by the liver, and its accumulation leads to lactic acidosis.
■Lactate Levels:
•Normal Range: 0.6-1.8 mmol/L
•Hyperlactatemia: 2-5 mmol/L
•Severe Lactic Acidosis: > 5 mmol/L
•Critical Threshold: Lactate > 8 mmol/L indicates high mortality risk.
■Physiology:
Lactate is produced at approximately 20 mmols/kg/day, entering circulation and undergoing hepatic and renal metabolism (Cori cycle). All tissues can produce lactate under anaerobic conditions, with significant contributions from skin, red cells, brain, muscle, and gut.
■Lactate Metabolism:
•Primarily metabolized in the liver (60%) and kidney (30%).
•The heart can also utilize lactate for ATP production.
•Converted into glucose (50%) or CO2 and water (50%) without net acid accumulation.
■Pathophysiology:
Lactic acidosis may arise from excessive tissue lactate production or impaired hepatic clearance, often seen in conditions like sepsis and ARDS. It is crucial to differentiate between Type A (inadequate oxygen delivery) and Type B (metabolic issues).
Type A
▪︎Causes:
•Anaerobic muscular activity (e.g., sprinting, convulsions)
•Tissue hypoperfusion (e.g., shock, cardiac arrest)
•Reduced oxygen delivery/utilization (e.g., hypoxaemia, CO poisoning)
Type B
▪︎Causes:
•B1: Underlying diseases like leukemia, thiamine deficiency, or hepatic failure.
•B2: Drugs and toxins including beta-agonists, methanol, or biguanides.
•B3: Inborn errors of metabolism.
Diagnosis:
Measuring plasma lactate levels is key, followed by identifying and treating the underlying cause. D-lactate, produced by intestinal bacteria, is a noteworthy isomer not detected by standard assays.
Management:
•Address the root cause and restore adequate oxygen delivery.
•Use bicarbonate cautious
