Patients on long-term home parenteral nutrition (HPN) are known to frequently develop hepatic steatosis or steatohepatitis. The etiology of this steatosis or steatohepatitis is unknown, but carnitine deficiency has been one of the postulated mechanisms. The importance of L-carnitine in hepatic fatty acid oxidation and the steatosis observed in primary and acquired carnitine deficiencies prompted us to determine plasma carnitine levels in 37 patients receiving long-term HPN. Thirteen patients (35%) had low total and free plasma carnitine levels. Fifteen of the 37 HPN patients were matched for age and sex with 15 patients with Crohn's disease who did not require HPN. Mean total and free plasma carnitine values were significantly lower (p less than 0.001) in these 15 HPN patients (32.2 +/- 11.9 and 28.4 +/- 10.8) when compared to Crohn's patients not requiring HPN (49.1 +/- 10.9 and 46.4 +/- 11.5). Associations were not detected between plasma carnitine and clinical or biochemical parameters that might have explained the low values.