MALA and metformin level

Q: A serum metformin level usually correlates with the severity of the poisoning, known as MALA (Metformin Associated Lactic Acidosis).

A) True

B) False

Answer: B

Serum metformin level is usually not ordered during suspected MALA for two reasons. First, it takes several days to report the level. Second, serum metformin concentrations typically do not correlate with the severity of toxicity or patient outcomes; however, a caveat of 'treatment bias' may be present, as by the time the level is reported, patients may be treated differently across institutions based solely on clinical signs and suspicion. Additionally, associated factors, such as renal insufficiency, may have played a role.

That said, some experts still advocate obtaining a serum metformin level, as it has a good negative predictive value. An undetectable metformin concentration basically rules out MALA.

#toxicity

#pharmacology

#acid-base

References:

1. Vecchio S, Giampreti A, Petrolini VM, et al. Metformin accumulation: lactic acidosis and high plasmatic metformin levels in a retrospective case series of 66 patients on chronic therapy. Clin Toxicol (Phila) 2014; 52:129.

2. Dell'Aglio DM, Perino LJ, Kazzi Z, et al. Acute metformin overdose: examining serum pH, lactate level, and metformin concentrations in survivors versus nonsurvivors: a systematic review of the literature. Ann Emerg Med 2009; 54:818.

3. Kajbaf F, De Broe ME, Lalau JD. Therapeutic Concentrations of Metformin: A Systematic Review. Clin Pharmacokinet 2016; 55:439.