Last reviewed 03/2023

Lactic acidosis should be suspected in a patient with a metabolic acidosis and a large anion gap which cannot be explained by:

  • urea
  • ketones
  • salicylates
  • methanol
  • ethylene glycol
  • paraldehyde

A lactate level of > 5.0 mM is considered diagnostic.

Incidentally, phosphate levels are usually high in lactic acidosis, averaging 2.9 mM.

Special investigations in type B lactic acidosis aim to determine the underlying condition:

  • blood is taken for:
    • full blood count, electrolytes and urea
    • culture
    • glucose determination
    • serum amylase
    • serum calcium
    • blood gases
    • group and save (in case there is unsuspected hypovolaemia)
  • ECG
  • microscopy and culture of urine