Abstract
Backgroundl-carnitine is essential for lipid metabolism, and lack of l-carnitine intake and loss by treatments lead to carnitine depletion causing muscle weakness, anemia, and immune dysfunction. Carnitine depletion occurs in critically ill patients after long treatments, but its epidemiology or the risk factors remain unclear. This study aims to investigate the prevalence and risk factors of l-carnitine depletion in critically ill patients.MethodsSixty-four patients were enrolled for the study. Total and free l-carnitine concentrations (t- and f-Carnitine) were measured at ICU admission and every 7 days afterward during hospitalization. Acylcarnitine- to f-Carnitine ratio (A/F Carnitine ratio) was analyzed in a subgroup of patients treated with continuous renal replacement therapy (CRRT). Acylcarnitine concentration was calculated as the difference between t- and f-Carnitine concentrations.ResultsCarnitine deficiency (f-Carnitine < 36 nmol/mL) was observed in 15 (23.4%) patients at ICU admission. Low body mass index (BMI < 19.5) was associated with a subsequent reduction of l-carnitine during the ICU stay (AUC = 0.81, p < 0.01). Sequential Organ Failure Assessment (SOFA) score was correlated with l-carnitine reduction but without a significant cutoff value. Patients treated with CRRT demonstrated elevated A/F Carnitine ratio (p < 0.05), possibly due to insufficient elimination or impaired metabolism of carnitine.ConclusionsLess than one fourth of critically ill patients had carnitine deficiency at ICU admission, while low BMI and high SOFA scores were identified as potential risk factors for reduction of l-carnitine. Patients treated with CRRT presented signs of impaired carnitine metabolism. Further studies to investigate the potential benefits of l-carnitine supplementation may be warranted in these patients.Trial registrationUMIN000013352. Registered 6 March 2014.
Highlights
L-carnitine is essential for lipid metabolism, and lack of L-carnitine intake and loss by treatments lead to carnitine depletion causing muscle weakness, anemia, and immune dysfunction
Sixty-four patients were enrolled in the study after excluding 224 post surgery patients, two patients under the age of 18, six patients who were readmitted to the intensive care unit (ICU), and five patients who were expected to die within 24 h, by the exclusion criteria
No significant differences were found between the low carnitine group and the normal carnitine group age, sex, body mass index (BMI), comorbidities, severity of the critical illness, or admission diagnoses (Table 1)
Summary
L-carnitine is essential for lipid metabolism, and lack of L-carnitine intake and loss by treatments lead to carnitine depletion causing muscle weakness, anemia, and immune dysfunction. Carnitine depletion occurs in critically ill patients after long treatments, but its epidemiology or the risk factors remain unclear. L-carnitine is an essential compound for energy utilization through lipid metabolism in the skeletal muscle [1]. It is mainly supplied through the regular diet, especially from animal meat and dairy products. It can be synthesized endogenously from lysine and methionine in the liver and the kidneys. Lack of L-carnitine impairs the utilization of fatty acid as energy source and leads to muscle weakness and muscle loss due to catabolism, which leads to deterioration of patients’ physical function
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