Acidosis in the hospital setting: is metformin a common precipitant?

BACKGROUND: Acidosis is commonly seen in the acute hospital setting, and carries a high mortality. Metformin has been associated with lactic acidosis, but it is unclear how frequently this is a cause of acidosis in hospitalized inpatients. The aim of this study is to explore the underlying comorbidities and acute precipitants of acidosis in the hospital setting, including the relationship between type 2 diabetes (T2DM) and metformin use.
METHODS: Retrospective review. Cases of acidosis were identified using the hospital discharge code for acidosis for a 3-month period: October-December 2005.
RESULTS: A total of 101 episodes of acidosis were identified: 29% had isolated respiratory acidosis, 31% had metabolic acidosis and 40% had a mixed respiratory and metabolic acidosis. There were 28 cases of confirmed lactic acidosis. Twenty-nine patients had T2DM, but only five of the subjects with T2DM had lactic acidosis; two were on metformin. The major risk factors for development of lactic acidosis were hepatic impairment (OR 33.8, P = 0.01), severe left ventricular dysfunction (OR 25.3, P = 0.074) and impaired renal function (OR 9.7, P = 0.09), but not metformin use.
CONCLUSION: Most cases of metabolic and lactic acidosis in the hospital setting occur in patients not taking metformin. Hepatic, renal and cardiac dysfunction are more important predictors for the development of acidosis.