Progressive Weakness and Hypoglycemia in a Child With Selective Eating: A Nutritional Mimic of a Fatty Acid Oxidation Disorder

Severe selective eating in children can lead to clinically important nutritional deficiencies. We report a 5-year-old boy with autism spectrum disorder who presented with progressive weakness and hypoglycemia mimicking a fatty acid oxidation disorder (FAOD). His diet had consisted almost exclusively of white rice, and he had developed clinically significant manifestations of folate and vitamin A deficiency before this presentation. After several months of progressive weakness, he developed a generalized seizure with severe hypoglycemia and blunted ketogenesis during an intercurrent infection. Laboratory testing showed low riboflavin, low free carnitine with an elevated acylcarnitine-to-free carnitine ratio, and mild C6-C10 acylcarnitine elevations. Nerve conduction studies suggested sensory-predominant axonal neuropathy. These findings resembled multiple acyl-CoA dehydrogenase deficiency, a FAOD. Riboflavin and levocarnitine supplementation was followed by recovery of independent walking, with no recurrence over 7 years. This case illustrates a nutritional mimic of FAODs and highlights the need for nutritional and metabolic evaluation in selectively eating children with progressive weakness or hypoglycemia.