Total carnitine and acylated carnitine ratio: relationship of free carnitine with lipid parameters in pediatric dialysis patients.

Carnitine has an essential role in the mitochondrial oxidation of long-chain fatty acids. Carnitine deficiency has been described in patients with chronic kidney disease. Total carnitine (TC) deficiency or a lower-than-normal ratio of free carnitine to acylated carnitine (FC:AC) has been shown to be associated with disorders in metabolism and plasma lipids. Metabolism and therapeutic use of carnitine have therefore been a major area of interest in dialysis patients. In a prospective observational study, we determined carnitine status (TC and FC:AC) and its correlations with lipid plasma levels in peritoneal dialysis (PD) and hemodialysis (HD) patients. In pediatric patients on chronic PD or HD, we evaluated nutritional status (weight and height), biochemical parameters (TC, FC, and AC levels), and fasting plasma lipoprotein concentrations. We studied 35 patients (16 boys, 19 girls; 25 on PD, 10 on HD). Median age was 5 years (range: 3 months-15 years). Median weight-to-height Z-score was -0.5 (range: -2.1 to 1.9), and median height-to-age Z-score was -2.5 (range: -0.3 to -2.9). The mean TC was 65.4 +/- 23.8 pg/mL (normal value: 40-55 pg/mL); the median AC was 18 pg/mL (range: 2-56pg/mL; normal value: 3-15 pg/mL); and the mean FC was 41.8 +/- 16.6 pg/mL (normal value: 25-35 pg/mL). Median serum FC:AC was 2.22 (range: 0.59-4.3; normal value: 4). A significantly higher AC and a lower FC:AC were observed in HD patients as compared with PD patients. No differences in TC and FC were observed when patients were grouped by dialysis modality, time on dialysis, or nutrition status. Total cholesterol was 200 mg/dL or higher in 20 patients, and 25 patients showed elevated triglycerides (> 150 mg/dL). The latter patients had a higher AC than did the group of patients with triglycerides below 150 mg/dL (AC: 22 pg/mL and 12.5 pg/mL respectively; Kruskal-Wallis p < 0.003). We found TC levels to be high in this group of patients. However, the FC:AC ratio was lower than normal in all except in 1 patient. Elevated triglycerides were associated with elevated AC, suggesting carnitine insufficiency in our patients.

Controlled study of enteral arginine supplementation in burned children: impact on immunologic and metabolic status.

OBJECTIVE: We compared the effects of an arginine-supplemented diet with those of an isocaloric isonitrogenous diet on immune and metabolic response of children with burns. METHODS: This was a double-blind, randomized, placebo-controlled trial in a burn treatment center of a pediatric hospital in Santiago, Chile. All children (1-5 y of age) admitted within 48 h of a moderate to deep burn injury covering 10% to 40% of total body surface area were evaluated. Twenty-eight children met the criteria and were randomly assigned to receive an arginine-supplemented diet (AG; n = 14) or an isocaloric isonitrogenous diet (CG; control, n = 14) for 14 d. Samples were collected at admission (baseline) and on days 7 and 14 for lymphoproliferative response to mitogens, plasma interleukins (interleukin-1, interleukin-6, tumor necrosis factor-alpha), plasma arginine and ornithine levels, serum C-reactive protein, prealbumin, albumin, glucose, and total urinary nitrogen. RESULTS: The AG enhanced lymphoproliferative responses (analysis of variance, P < 0.05), which were 72% of normal at baseline in both groups; by day 7 responses increased to 144% in the AG group and decreased to 56% in the CG group; both groups returned to normal by day 14. Baseline interleukin-6 was significantly increased in all children. There were no differences in plasma concentrations of interleukin-1, interleukin-6, tumor necrosis factor-alpha, C-reactive protein, prealbumin, albumin, or glucose between the AG and CG groups. On day 7 plasma ornithine levels increased significantly in the AG versus CG group (P < 0.05); arginine levels showed no change. CONCLUSIONS: An exclusively AG improves mitogen-stimulated lymphocyte proliferation in burned children. The benefits of arginine for the immune system do not appear to be related to a metabolic response. The biological significance of this finding remains to be determined.

Energy expenditure, nutrition status, and body composition in children with cystic fibrosis.

OBJECTIVE: Undernutrition is a frequent complication in patients with cystic fibrosis (CF). Elevated energy requirements have been found to be 4% to 33% higher than in controls in some studies. Whether or not this is caused by a primary defect or energy metabolism is still a matter of controversy. To this end, we assessed energy expenditure, nutrition status, and body composition of clinically stable CF outpatients. METHODS: Fifteen clinically stable CF patients, ages 2 to 15 y, were paired with 15 healthy control children. Measurements consisted of anthropometry and body composition. Plasma tocopherol, retinol, and hair zinc content were measured. Resting energy expenditure was determined by indirect calorimetry. Physical activity and dietary intake were recorded by recall methods. RESULTS: Two children were nutritionally at risk according to the weight/height index, eight were normal, three were overweight, and two were obese. Body composition was similar in both groups. Zinc, tocopherol, and retinol levels were low in three, two, and three patients, respectively. Resting energy expenditures were 4.7 MJ/d (1127 +/- 220 kcal/d) in CF children and 4.63 MJ/d (1108 +/- 191 kcal/d) in control children (P = not significant). Physical activity level was sedentary in 86.6% of CF patients; the rest had a light physical activity pattern. Energy intake represented 141% of the estimated daily energy expenditure. CONCLUSIONS: Non-oxygen-dependent CF children, without acute respiratory infection, had resting energy expenditures comparable to those of matched controls. Total energy expenditure was similar to or slightly lower than that in healthy children. Dietary recommendations for CF patients need to be reassessed.