Effective Extracorporeal Treatment of Metformin-Associated Lactic Acidosis using Continuous Venovenous Hemodiafiltration.

Background: The prevalence of type 2 diabetes mellitus has surged globally. Metformin is recommended as the first-line oral treatment. However, metformin-associated lactic acidosis (MALA) is recognized as a rare but potentially dangerous complication. The pathogenesis of MALA is multifactorial, primarily resulting from the interference of metformin with mitochondrial function and hepatic gluconeogenesis, leading to lactate accumulation. Risk of MALA escalates with impaired kidney function, poorly controlled diabetes, fasting, and liver dysfunction.

Case description: A 57-year-old woman with diabetes and hypertension presented with prolonged gastrointestinal symptoms. During this episode she continued using metformin. She had severe metabolic acidosis and acute kidney injury. Continuous venovenous hemodiafiltration was initiated, resulting in significant clinical improvement and normalized arterial blood gas parameters within 16 hours.

Discussion: The pharmacokinetic properties of metformin facilitate efficient elimination via hemodialysis and/or hemofiltration. Continuous venovenous hemodiafiltration emerges as effective for MALA treatment. In the case described the calculated metformin clearance during continuous venovenous hemodiafiltration was notably higher than reported values, possibly due to residual renal clearance. Clinical improvement occurred despite elevated metformin levels, suggesting a lack of correlation between metformin levels and patient outcomes. Comorbidities rather than metformin levels guide treatment decisions in MALA.

Conclusion: This case underscores the efficacy of continuous venovenous hemodiafiltration in the treatment of MALA, suggesting its potential as a standard therapeutic approach. However, further research is needed to elucidate the complex interplay between metformin levels, clinical presentation, (extracorporeal) treatment modalities and outcome in MALA.

Learning points: Continuous venovenous hemodiafiltration seems to be an efficient and effective treatment to eliminate metformin in patients with metformin-associated lactic acidosis.The metformin level does not seem to correlate with the clinical condition of the patient.For a comparison between the effectiveness of different renal replacement therapies in metformin-associated lactic acidosis, more research is needed.