An 8-month-old boy is evaluated for developmental delay, failure to thrive, and episodic seizures. Physical examination shows ophthalmoplegia and hypotonia. Laboratory studies reveal an elevated serum lactate level. Further histochemical studies show severely reduced pyruvate dehydrogenase enzyme activity in both freshly isolated peripheral blood lymphocytes and cultured fibroblasts. Increasing which of the following substances in his diet is most likely to help this patient generate energy without further elevating lactate levels?

Question

An 8-month-old boy is evaluated for developmental delay, failure to thrive, and episodic seizures.  Physical examination shows ophthalmoplegia and hypotonia.  Laboratory studies reveal an elevated serum lactate level.  Further histochemical studies show severely reduced pyruvate dehydrogenase enzyme activity in both freshly isolated peripheral blood lymphocytes and cultured fibroblasts.  Increasing which of the following substances in his diet is most likely to help this patient generate energy without further elevating lactate levels?

Quizplus · Accepted Answer

Eductional Objective: Pyruvate dehydrogenase complex deficiency is an inherited inborn error of metabolism causing lactic acidosis and neurologic defects.  Patients are unable to convert pyruvate to acetyl-CoA, resulting in a shunting of pyruvate to lactic acid.  In these patients, metabolism of exclusively ketogenic amino acids (eg, lysine, leucine) can provide energy in the form of acetyl-CoA without increasing lactate production.

An 8-Month-Old Boy Is Evaluated for Developmental Delay, Failure to Thrive