Low blood and plasma carnitine levels in children receiving long-term parenteral nutrition

Total and free carnitine and acylcarnitine concentrations were analyzed in whole blood and plasma in 12 children with a mean age of 68.4 +/- 42.9 months who had received carnitine-free total parenteral nutrition (TPN) for an average of 4 years. The purpose of the study was to see if the children had become carnitine deficient and, if so, whether this correlated with poor lipid clearance. Compared to controls, the TPN-dependent children had significantly decreased concentrations of total and free carnitine in blood (26.6 +/- 9.4 (SD) mumols/L vs. 43.3 +/- 9.1 mumols/L, p less than 0.001, and 17.1 +/- 7.7 mumols/L vs. 35.2 +/- 8.1 mumols/L, p less than 0.001, respectively). Similar results were found in plasma (total carnitine of 19.0 +/- 8.0 mumols/L vs. 41.9 +/- 5.2 mumols/L, p less than 0.001, and free carnitine of 15.7 +/- 7.3 mumols/L vs. 36.1 +/- 5.2 mumols/L, p less than 0.001, respectively). The acylcarnitine concentration in plasma was decreased in the TPN children (3.3 +/- 1.5 mumols/L vs. 5.8 +/- 3.0 mumols/L, p less than 0.01) compared to controls. Despite the low carnitine concentrations, serum triglyceride levels and serum free fatty acid levels were within the normal range. There was no correlation between carnitine concentrations in plasma and serum triglyceride and free fatty acid levels. Our data show that children receiving carnitine-free TPN for many years developed markedly decreased concentrations of carnitine in blood and plasma. However, no adverse effects of the low carnitine levels were found on triglyceride and free fatty acid metabolism under stable conditions.