Intestinal Cholesterol Absorption Inhibitor Ezetimibe Added to Cholestyramine for Sitosterolemia and Xanthomatosis

Sitosterolemia is a rare, recessively inherited disorder characterized by increased absorption and delayed removal of noncholesterol sterols, which is associated with accelerated atherosclerosis, premature coronary artery disease, hemolysis, and xanthomatosis. Treatments include low-sterol diet and bile salt-binding resins; however, these often do not reduce the xanthomatosis. We examined the effects of the intestinal cholesterol/phytosterol transporter inhibitor ezetimibe added to cholestyramine in a young female patient with sitosterolemia and associated xanthomatosis. The patient was an 11-year-old female with sitosterolemia presenting with prominent xanthomas in the subcutaneous tissue of both elbows who was receiving treatment with cholestyramine 2 g once daily. Bilateral carotid bruits were audible, and a grade II/VI systolic murmur was detected at the left upper sternal border. She also had a low platelet count of 111,000/μL. Ezetimibe 10 mg once daily was added to the patient’s ongoing cholestyramine regimen, and she was evaluated for 1 year. The patient followed an unrestricted diet during the 1-year treatment period. After 1 year of treatment with ezetimibe added to ongoing cholestyramine therapy, the patient’s plasma sitosterol and campesterol levels decreased by approximately 50%. Her carotid bruits completely resolved, her systolic murmur diminished, and her platelet count rose to 268,000/μL. More remarkably, the tuberous xanthomas on her elbows had completely regressed. Ezetimibe added to ongoing low-dose cholestyramine therapy led to a marked improvement in plasma sterol concentrations, complete regression of xanthomatosis, resolution of carotid bruits, and improvement in cardiac murmur in a young female patient with sitosterolemia.