Metabolic studies of a 9-year-old girl with primary type V hyperlipoproteinemia demonstrated normal glucose tolerance, plasma insulin and glucagon responses to stimuli, and serum uric acid level. Fasting plasma triglyceride levels rapidly increased when the patient received a diet containing 40% of the total calories as fat and rapidly decreased on a 10% fat diet. Hepatic and nonhepatic lipase activities in postheparin plasma were normal, thus excluding type I hyperlipoproteinemia. Because of the potential complication of acute pancreatitis in this disorder, early diagnosis and prompt institution of diet therapy is important.
