Classic ketogenic diet-induced ketoacidosis in the treatment of pyruvate dehydrogenase deficiency: a case report and literature review.

Background: As a rare mitochondrial disorder, the pyruvate dehydrogenase complex (PDC) deficiency is a rare inborn disease characterized with glucose metabolism defects, which leads to neurological dysfunction, serum lactic acid buildup and a resultant trend of metabolic acidosis. Although the ketogenic diet (KD) is the first-line treatment for PDC deficiency, there is currently no widely accepted consensus on specific implementation of KD for this condition. Due to the combined effect of pre-existing hyperlactacidemia and KD-induced ketoacidosis that can further exacerbate metabolic disturbances, maintaining metabolic homeostasis should be prioritized during the implementation of KD.

Case presentation: Herein, the authors present a 6-year-old boy with lactic acidosis, ataxia, hypotonia and neuromotor development retardation. The KD was started after the patient was diagnosed with PDC deficiency based on genetic testing. The initiation with classic KD resulted in severe non-diabetic ketoacidosis with elevated anion gap, which was promptly alleviated by dextrose supplementation and dietary modification to a less-restrictive KD. Long-term supervision demonstrated the efficacy of a modified KD in improving both clinical course and metabolic acidosis of the patient.

Conclusions: This rare case adds to the limited evidence of KD application in PDC deficiency, and provides valuable insights into the importance of reasonably lowering the ketogenic ratio of KD at the start of treatment to reduce the risk of metabolic acidosis.