Abstract
A stay in intensive care unit (ICU) exposes patients to a risk of carnitine deficiency. Moreover, acylated derivates of carnitine (acylcarnitines, AC) are biomarkers for metabolic mitochondrial dysfunction that have been linked to post-ICU disorders. This study aimed to describe the AC profile of survivors of a prolonged ICU stay (≥7 days). Survivors enrolled in our post-ICU clinic between September 2020 and July 2021 were included. Blood analysis was routinely performed during the days after ICU discharge, focusing on metabolic markers and including AC profile. Serum AC concentrations were determined by LC-MS/MS and were compared to the reference ranges (RR) established from serum samples of 50 non-hospitalized Belgian adults aged from 18 to 81 years. A total 162 patients (65.4% males, age 67 (58.7–73) years) survived an ICU stay of 9.7 (7.1–19.3) days and were evaluated 5 (3–8) days after discharge. Their AC profile was significantly different compared to RR, mostly in terms of short chain AC: the sum of C3, C4 and C5 derivates reached 1.36 (0.98–1.99) and 0.86 (0.66–0.99) µmol/L respectively (p < 0.001). Free carnitine (C0) concentration of survivors (46.06 (35.04–56.35) µmol/L) was similar to RR (43.64 (36.43–52.96) µmol/L) (p = 0.55). C0 below percentile 2.5 of RR was observed in 6/162 (3.7%) survivors. Their total AC/C0 ratio was 0.33 (0.22–0.42). A ratio above 0.4 was observed in 45/162 (27.8%) patients. In ICU survivors, carnitine deficiency was rare, but AC profile was altered and AC/C0 ratio was abnormal in more than 25%. The value of AC profile as a marker of post-ICU dysmetabolism needs further investigations.
Highlights
Publisher’s Note: MDPI stays neutralCarnitine, a naturally occurring amino acid derivative, is a low molecular weight molecule that exists as two enantiomers: D- and L-carnitine; only the L-isomer is physiologically active
In intensive care unit (ICU) survivors, carnitine deficiency was rare, but AC profile was altered and AC/C0 ratio was abnormal in more than 25%
Carnitine acts as a scavenger, binding acyl residues deriving from the intermediary metabolism of amino acids and facilitating their elimination
Summary
A naturally occurring amino acid derivative, is a low molecular weight molecule that exists as two enantiomers: D- and L-carnitine; only the L-isomer is physiologically active. Carnitine may be obtained from dietary sources (75%) and is synthesized endogenously in the body (25%), predominantly in the liver [1]. Carnitine plays a critical role in cellular energy metabolism and in maintenance of free coenzyme A availability. Its main function is the transport of long-chain fatty acids into mitochondria, where they will undergo subsequent β-oxidation. Carnitine acts as a scavenger, binding acyl residues deriving from the intermediary metabolism of amino acids and facilitating their elimination. Both roles of carnitine result in its esterification into acylcarnitine derivatives
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