Carnitine metabolites in infants with cystic fibrosis: a prospective study

Abstract

Acylcarnitine is low in cord blood in patients with cystic fibrosis, suggesting that fatty acid metabolism is disturbed in utero. Carnitine metabolites (total, free, short- and long-chain acylcarnitine) were measured prospectively in 23 newly diagnosed infants with cystic fibrosis treated with a carnitine-containing, predigested formula for 6-12 months. Total (p < 0.002), free (p < 0.004), and long-chain (p < 0.001) plasma concentrations of carnitines were significantly less than controls (n = 48) at diagnosis. Total and free concentrations were corrected with nutritional management, whereas short- and long-chain acylcarnitines remained unchanged. By three years of age all plasma concentrations of carnitine metabolites were significantly less than controls despite a carnitine-containing diet. Urinary carnitine metabolites were increased at diagnosis and follow-up. The physiological significance of these observations in cystic fibrosis is unknown, but could be compatible with disturbed regulatory control with resultant increased utilization.

Perinatal Reduced Blood Concentrations of Free Carnitine and Acylcarnitines in Infants with Cystic Fibrosis

“…Although a comparison with controls on the fifth day of life was not feasible, it is meaningful to consider that FC and tAC concentrations would be much higher as compared with those of CF infants. The current findings in perinatal period increase the significance of the results of the previous studies, 13,14 as they originate from a larger and well-characterized cohort and describe the status of the first days of life.…”

“…As previously mentioned, tAC (short-and long-chain combined) were determined remarkably reduced in the cord blood of CF newborns compared with non-CF siblings and controls, suggesting that FA metabolism is disturbed in utero. 13 The same authors provided further evidence 14 for disturbed carnitine metabolism in CF patients.…”

“…These findings could be related to a disturbance of FA metabolism during pregnancy. Later, the same authors 14 measured the carnitines in plasma of 23 CF newly diagnosed infants (mean age ¼ 4 months) using a radioenzymatic assay. Low concentrations of free, total, and long-chain plasma concentrations of acylcarnitines were determined in CF infants, indicating disturbed regulatory control with resultant increased utilization.…”

Nutritional management of cystic fibrosis.

“…Failure to thrive, hypoalbuminaemia56 and even kwashiorkor57 are seen in unscreened infants, whereas nutritional deficits in screened infants are more subtle, but include reduced body mass, length, total body fat, total body potassium58 and low levels of tocopherol, linoleic acid,59 serum retinol, 25-hydroxyvitamin D,60 and plasma carnitine. 61 We find most infants with pancreatic insufficiency will thrive on a normal energy intake of 100-130 kcal/kg in adjunct with pancreatic enzymes. If weight gain is less than expected or if a meconium ileus has resulted in surgery and bowel resection, the energy requirements may be as high as 150-200 kcal/kg.…”