SERUM LATHOSTEROL LEVELS IN HUMAN-SUBJECTS REFLECT CHANGES IN WHOLE-BODY CHOLESTEROL-SYNTHESIS INDUCED BY LOVASTATIN BUT NOT DIETARY-CHOLESTEROL

We measured serum lathosterol levels and whole body cholesterol synthe sis by sterol balance in 12 human subjects on a metabolic ward in four randomly allocated, 6-7 week periods: 1) lovastatin (40 mg b.i.d) + l ow cholesterol diet (mean 246 mg/day); 2)lovastatin + high cholesterol diet (mean 1071 mg/day); 3) low cholesterol diet alone; and 4) high c holesterol diet alone. Whole body cholesterol synthesis was significan tly reduced both by lovastatin (P = 0.0004) and by high dietary choles terol (P = 0.0005). Serum total lathosterol (mu g/dl) was reduced by l ovastatin (P < 0.0001), but was not significantly altered (and actuall y tended to increase) during consumption of the high cholesterol diet, presumably because eggs contained appreciable lathosterol as demonstr ated by direct analysis. Results were similar for total versus free la thosterol and for lathosterol expressed as mu g/dl serum versus mu g/1 00 mg cholesterol. We conclude that serum lathosterol does not reflect changes in cholesterol synthesis induced by dietary cholesterol. Stud ies using serum lathosterol as an indicator of cholesterol synthesis m ust be carefully controlled for dietary cholesterol.