Lactic Acidosis Flashcards
lactate generation
originates from red cells, skeletal muscle, brain and renal medulla
it is the end product of anaerobic metabolism of glucose
clearance of it requires hepatic uptake and aerobic conversion to pyruvate then glucose
what is the normal range for lactate
0.6 -1.2 mmol/L
what happens to lactate levels in the fasted state and during severe exercise
generally lowest in the fasted state
severe exercise - can rise up to 10mmol/L
at what lactate level is acidosis more likely
>5 mmol/L
Type A
associated with tissue hypoxaemia
- infarcted tissue eg bowel
- cardiogenic shock
- hypovolaemic shock: sepsis (endotoxic) and haemorrhage
Type B
acidosis occuring when there is no clinical evidence of poor tissue perfusion or hypoxaemia
may occur in liver disease/leukaemic states
associated with diabetes - 10% of DKA cases have lactate >5mmol/L
what should one consider if lactic acidosis and patient is well and non-diabetic
rare inherited metbolic condition
metformin and lactic acidosis
metformin can cause lactic acidosis in severe illness states or renal failure
clinical features
hyperventilation - trying to restore metabolic acidosis by breathing off CO2
mental confusion
stupor/coma if severe
lab findings
reduced bicarbonate
raised anion gap
glucose variable
absence of ketonaemia
raised phosphate
anion gap
[(Na+ + K+) – (HCO3 + Cl-)]
estimates unmeasured plasma anions (fixed/organic acids such as phosphate, ketones and lactate, which are hard to measure directly)
raised anion gap
Due to increased production, or reduced excretion of fixed/organic acids. HCO3- falls and unmeasured anions associated with the acids accumulate.
causes of raised anion gap
ketones (DM/alcohol)
uraemia (renal failure)
lactic acid (shock, infection, tissue ischaemia)
starvation
drugs/toxins (ethylene glycol, methanol, salicylate or paraldehyde poisoning)
treatment
underlying condition: fluids and antibiotics
withdraw offending medication
alcohol ketoacidosis
metabolic complication of alcohol use and starvation characterised by hyperketonaemia and raised anion gap metabolic acidosis without significant hyperglycaemia
- alcohol diminishes hepatic gluconeogenesis which causes less insulin to be produced. the body breaks down fats for energy and produces ketones as by-products
