The importance of recognizing secondary carnitine deficiency in organic acidaemias: case report in glutaric acidaemia type II.

Secondary carnitine deficiency in a patient with glutaric acidaemia type II, due to deficient ETF-dehydrogenase activity, is described. The patient responded clinically to a pharmacological dose of riboflavin and a restricted protein diet. In the second year of her life she developed more frequent and severe exacerbations during intercurrent infections from which she did not fully recover. Hypotonia and marked ataxia persisted. Plasma carnitine was entirely complexed as acylcarnitine with no free carnitine detected. Retrospective evaluation of several frozen urine specimens obtained since the age of 10 months revealed undetectable free carnitine with elevated acylcarnitine levels. Marked clinical improvement was observed following L-carnitine supplementation. The hypotonia and ataxia disappeared. The frequency and the severity of the exacerbations were noticeably decreased. The role of L-carnitine in preventing the accumulation of acyl-CoA compounds in inborn errors of organic acid metabolism is further emphasized by this patient. The necessity to evaluate free carnitine, acylcarnitine and acyl/free ratio in the assessment, follow-up and management of patients with inborn errors of organic acid metabolism is discussed.