Carnitine deficiency in children receiving continuous renal replacement therapy

Carnitine deficiency is known to occur in chronic hemodialysis; however, the effect of continuous renal replacement therapy (CRRT) on carnitine homeostasis has not been studied. We hypothesized that children receiving CRRT are at risk for deficiency because of continuous removal, absent intake, decreased production, and comorbidities related to critical illness. Records of patients with acute kidney injury receiving CRRT at Children's National Health System between 2011 and 2014 were reviewed for total carnitine (TC), free carnitine (FC), feeding modality, severity of illness, and survival outcome. The proportion of carnitine-deficient patients at baseline, 1, 2, and 3 weeks on CRRT were compared by chi-square, and relationships with other variables assessed by Pearson's correlation and logistic regression. The study group included 42 CRRT patients, age 7.9+1.1 years. At baseline, 30.7% and 35.7% of patients were TC and FC deficient. Within 1 week, 64.5% (P=0.03) and 70% (P=0.03) were TC and FC deficient, and prevalence of deficiency increased to 80% (P=0.01) and 90% (P=0.008) by 2 weeks; 100% of patients were TC and FC deficient after being on CRRT for 3 weeks (P=0.005 and P=0.01, respectively, vs. baseline). TC and FC levels negatively correlated with days on CRRT (r=-0.39, P=0.001 and r=-0.35, P=0.005). Patients with TC and FC deficiency had 5.9 and 4.9 greater odds of death than those with normal levels (P=0.02 and P=0.03). Carnitine is significantly and rapidly depleted with longer time on CRRT, and carnitine deficiency is associated with increased mortality. Consequences of deficiency and benefits of supplementation in the pediatric CRRT population should be investigated.