Free and esterified carnitine in continuous ambulatory peritoneal dialysis patients

Abstract

Free, acetyl-, medium- and long-chain acylcarnitine and total plasma carnitine concentrations were measured in eight continuous ambulatory peritoneal dialysis (CAPD) patients and eight age- and sex-matched healthy controls. Daily loss of carnitine was also quantified in both groups, by analysis of urine and dialysis fluid. Plasma total carnitine concentration in CAPD patients was not significantly different from controls (42.8 +/- 1.6 and 43.1 +/- 2.3 mumol/liter, respectively). However, the plasma free carnitine concentration of CAPD patients was significantly lower than that of controls (28.5 +/- 1.4 and 36.2 +/- 2.5 mumol/liter, respectively; P < 0.05). No difference in the daily loss of total carnitine was found between CAPD patients and controls (269.7 +/- 30.0 and 240.5 +/-33.0 mumol/liter, respectively), but the daily loss of free carnitine was significantly greater in CAPD patients (175.8 +/- 17.3 and 105.8 +/- 16.4 mumol/liter, respectively; P < 0.05). The ratio of total acylcarnitine (acetyl-, medium- and long-chain acylcarnitine) to free carnitine was significantly greater in plasma of CAPD patients than in controls (P < 0.01) and was lower in daily fluid losses (P < 0.001). These ratio differences suggests that an alteration in acyl group metabolism is occurring in CAPD patients. This may be attributable to an accumulation of medium- and long-chain acylcarnitine in liver of CAPD patients which would be exchanged for plasma free carnitine and/or to a differential loss of free and acylcarnitine across the peritoneal cavity.

Carnitine supplementation improves apolipoprotein B levels in pediatric peritoneal dialysis patients

“…PD patients in the present series had lower FC and higher AC values than healthy children in the control group. Similar to our findings, low FC and high AC levels, resulting in a high AC/FC ratio, were noted in adult patients receiving PD [15,16]. In healthy individuals, 90% of FC in the ultrafiltrate in Bowman's space is absorbed by the proximal tubule.…”

“…After 15 min, following the addition of 20 l of carnitine acetyl transferase, the absorbance was read by Secomam S. 7501 spectrophotometer. AC concentrations were calculated as AC=TCFC [16].…”

“…Normal [6,7,8,9], low [10], and high [11] plasma total carnitine (TC) levels have been reported. Also, studies analyzing plasma levels of free and esterified carnitine fractions in continuous ambulatory PD (CAPD) patients have noted either normal [12,13,14] or low [13,14,15,16] free carnitine (FC) levels and a high ratio of acyl-carnitine (AC) to FC [16]. Only three studies, involving 34 patients, have been published describing the carnitine status of pediatric PD patients [17,18,19].…”

Effect of carnitine supplementation on lipid profile and anemia in children on chronic dialysis

“…Similar results have also been reported by another pediatric study [12]. A higher loss of FC in the dialysate may be expected in patients on continuous regimens of PD [18] than in those on an intermittent regimen. Also, individual characteristics of the peritoneal membrane were reported to influence the loss of FC and acylcarnitine in the dialysate [23].…”

“…Data in PD patients are very scanty. Constantin-Teodosiu et al [18] have shown low plasma FC and increased acylcarnitine/FC ratio in adult PD patients; daily losses of FC in the peritoneal dialysate are likely to contribute significantly to this condition.…”