Prevalence of carnitine depletion in critically ill patients with undernutrition

Abstract

The aim of this study was to evaluate to what extent secondary carnitine deficiency may exist based on the prevalence of subnormal carnitine status in patients with critical illness and abnormal nutritional state. Healthy control patients (n = 12) were investigated and compared with patients with possible secondary carnitine deficiency, ie, patients with overt severe protein-energy malnutrition (PEM, n = 28), postoperative long-term (> 14 days) parenteral glucose feeding (250 g glucose/d, n = 7), severe liver disease (n = 10), renal insufficiency (n = 7), and sustained septicemia with increased metabolic rate (n = 8). Nutritional status, energy expenditure, creatinine excretion, and blood biochemical tests were measured in relationship to free and total carnitine concentrations in plasma and skeletal muscle tissue, as well as urinary excretion of free and total carnitine. The overall mortality rate was 48% within 30 days of the investigation in study patients with the highest mortality in liver disease (90%). The hospitalization range was 14 to 129 days in study patients. Most study patients had lost weight (4% to 19%) and had abnormal body composition. Patients with liver disease, septicemia, renal insufficiency, and those on long-term glucose feeding had significantly higher than predicted metabolic rate (+25% ± 3%), while patients with severe malnutrition had decreased metabolic rate compared with controls. Patients with liver disease had increased plasma concentrations of free (96 ± 16 μmol/L) and total (144 ± 27 μmol/L) carnitine compared with controls (45 ± 3,58 ± 7 μmol/L, respectively). No other differences among the groups were seen in plasma or muscle carnitine concentrations as compared with control patients, although some patient groups (liver disease, sever PEM, long-term glucose feeding) showed indices of increased free and total carnitine excretion. There was no correlation between muscle and plasma carnitine concentrations. The present study demonstrates that the overall prevalence of statistically significant carnitine depletion was less than 5% in a large heterogeneous group of patients suffering from critical illness and abnormal nutritional state.