Serum carnitine concentration and the acyl to free carnitine ratio in nondialysis chronic kidney disease and hemodialysis patients

Abstract

Mechanisms of impaired fatty acid metabolism may not be the same in nondialysis and hemodialysis patients. Correlations between the serum‐free carnitine concentration (FC), acylcarnitine concentration (AC), acyl to free carnitine ratio (AC/FC), and estimated glomerular filtration rate (eGFR) in the nondialysis population and the duration of hemodialysis in hemodialysis patients were investigated. As the eGFR decreased, the FC and AC increased, and as the duration of hemodialysis became longer, the FC and AC decreased. The AC/FC increased consistently as the eGFR decreased and the duration of hemodialysis increased. As an exception, the AC/FC decreased in the patients with a hemodialysis duration less than 90 days, which was not explained by carnitine removal by hemodialysis. In nondialysis patients, a functional, rather than an absolute, carnitine deficiency is a main cause of impaired fatty acid metabolism. Long‐term hemodialysis exacerbates absolute carnitine deficiency, whereas hemodialysis treatment may improve impaired fatty acid metabolism.

Nocturnal Leg Cramping Caused by Carnitine Deficiency Due to Long-Term Pivalate Antibiotics Administration in a Patient With Chronic Kidney Disease

“…In non-dialysis CKD patients, reduced selective urinary excretion of AC and impaired ß-oxidation lead to the accumulation of excess acyl groups [ 12 ]. To protect the mitochondria from toxic damage from excess acyl groups, FC is esterified to AC to buffer the excess acyl groups, resulting in increased AC levels and the resultant elevated AC/FC ratio, which indicates functional or relative carnitine deficiency [ 6 ]. In our patient, not only the serum FC level but also the AC concentration had decreased before L-carnitine treatment.…”

“…Leg cramping due to carnitine deficiency in adults is more common in patients undergoing peritoneal dialysis [ 4 ] and hemodialysis [ 5 ] and is mainly caused by insufficient dietary carnitine intake secondary to protein restriction and removal of carnitine from the blood as part of the dialysis process. In patients with non-dialysis chronic kidney disease (CKD), despite a restriction of protein intake and decreased biosynthesis of carnitine, free-carnitine (FC) levels do not drop with declining renal function, leading to reduced urinary excretion of carnitine relative to its intake [ 6 ].…”

Abnormal carnitine metabolism in hemodialysis patients on different anticoagulants

“…A higher AC/FC ratio indicates an intracellular carnitine deficiency. The AC/FC ratio is therefore a critical marker in evaluating carnitine deficiency within cellular environments [3][4][5].…”