Changes of plasma levels of apolipoproteins A-I, A-II, and B and their isoforms in patients with intestinal failure receiving long-term parenteral nutrition.

We have studied the plasma lipid and apolipoprotein profiles of 19 patients with intestinal failure who are receiving long-term total parenteral nutrition (TPN). These patients had significantly reduced levels of total and HDL cholesterol and normal levels of triglycerides. Radioimmunoassay determination of apolipoproteins showed a 30% and 50% reduction in apo A-I and A-II levels, respectively. Apolipoprotein B was normal in all but three patients. Isoelectric focusing showed two major isoforms of apo A-I in patients as compared with four isoforms observed in normal subjects and one major isoform of apo A-II compared with multiple isoforms. Recent epidemiologic studies indicate that an increased apo B:apo A-I ratio may be an important factor in atherogenesis. We suggest that patients with small-bowel syndrome who are currently on TPN may be at greater risk for atherosclerosis. Since TPN has restored a reasonably normal life expectancy for these patients, long-term follow-up will likely provide answers.