Serum carnitine concentrations in different glomerular diseases with normal renal function

Serum carnitine concentrations are known to decrease in patients on regular hemodialysis and to increase in chronic renal failure. However, there is little information available concerning serum levels of carnitine in different glomerular diseases in patients whose renal functions have not yet deteriorated. In this study, we measured serum carnitine concentrations in 40 pediatric patients with idiopathic nephrotic syndrome, IgA nephropathy, non-IgA glomerulonephritis, focal segmental glomerular sclerosis, and normal controls. The results showed that there were no significant differences in the serum-free and total carnitine concentrations (S-FCC and S-TCC, respectively) between patients with different glomerular diseases and the controls. Of interest was the statistically weak correlations of both S-TCC and S-FCC with BUN in these patients, despite their normal renal functions. The ratio of S-FCC to S-TCC was significantly higher as compared with that of the controls. These findings suggest that serum carnitine concentrations are not affected by the types of glomerular lesions and that serum levels of carnitine depend mostly on the glomerular excretory capacity of urea nitrogens, even when the renal functions have not yet deteriorated. The increase in the ratio of S-FCC to S-TCC may be an early reflection of changes in the serum carnitine profiles of these patients.