CHOLESTEROL-METABOLISM IN FAMILIAL HYPERTRIGLYCERIDEMIA - EFFECTS OF OBESITY VERSUS TRIGLYCERIDE LEVEL

Excessive production of cholesterol has been associated with type IV h yperlipidemia, but the influence of the confounding variable of obesit y has been difficult to ascertain. Moreover, cholesterol metabolism ha s not been systematically evaluated in patients with familial hypertri glyceridemia (FHT), one of the two major subsets of type IV patients. We used isotope dilution to measure cholesterol production, pools, and kinetic constants in 8 hypertriglyceridemic subjects, 6 of whom could be confidently classified as FHT. These were compared with measuremen ts in 9 control subjects matched for sex, age, serum cholesterol, and body mass index (BMI). By t test, hypertriglyceridemic subjects did no t differ from controls with respect to cholesterol production, size of readily or slowly miscible pools, or kinetic transfer coefficients. R esults were the same whether controls were compared with all hypertrig lyceridemic patients or only the 6 with definite FHT. By analysis of c ovariance (ANCOVA), serum triglyceride level was not a significant det erminant of any parameter of cholesterol metabolism. However, BMI was a highly significant determinant of cholesterol production (p = 0.0001 ) and size of both readily and slowly miscible pools (p = 0.001 to 0.0 08). These data suggest that FHT per se is not associated with abnorma lities of cholesterol metabolism but that an apparent association coul d result from the confounding variable of obesity.