Approach Considerations
Treatment of sitosterolemia may include dietary changes, pharmacologic agents, and/or surgical intervention. A diet low in plant sterols may be recommended. Bile acid-binding resins may be administered. An ileal bypass may be indicated. However, even with treatment, plant sterol levels may not be reduced to normal. [32] Ezetimibe is the treatment of choice. After 3 years of treatment in a young child, carotid artery intima media thickness (cIMT) was stable in diameter and arterial wall echogenicity had improved. [33] Arthritis may require treatment. Treat chronic anemia and/or thrombocytopenia, if present. In at least one case, ezetimibe and a PCSK9 inhibitor along with a low-plant-sterol diet successfully reduced serum levels of low-density lipoprotein cholesterol. [12] A recent series with clinical, genetic, and therapeutic data reported excellent results with varying combinations of dietary treatment and Ezetimibe in 55 children and 5 adults. [34]
Medical Care
Medications are occasionally used in the treatment of sitosterolemia. Dietary therapy was formerly the recommended initial treatment, but newer therapies have supplanted dietary therapy. If dietary treatment alone is attempted and insufficient, bile acid-binding resins (eg, cholestyramine) could be considered.
In October 2002, ezetimibe, a cholesterol absorption inhibitor, received US Food and Drug Administration (FDA) approval for use in sitosterolemia. Because the mechanism by which it inhibits cholesterol absorption is quite specific, the adverse effects and drug interactions associated with the resins should not be expected.
Ezetimibe can increase platelet count and decrease mean platelet volume, thereby potentially reducing the risk for bleeding in sitosterolemia. [35]
A multiple center collaborative randomized placebo-controlled study of ezetimibe 10 mg/d in patients aged 10 years and older determined that ezetimibe was well tolerated and efficacious in reducing plant sterol levels compared with a placebo. [36] Plasma cholesterol levels, if elevated, fall dramatically in patients treated with ezetimibe. Plasma plant sterol levels fall also but often not to normal levels.
A study in China documented the successful use of ezetimibe in several young children, although a child younger than 2 years initially did not respond. [5] The long-term efficacy and safety of ezetimibe in sitosterolemia have been documented. [37] In contrast with patients with adult sitosterolemia who typically reached full treatment response within 2–8 weeks of treatment, [36] 4 months of treatment was required to significantly lower the sterols in the children reported in the study in China.
Little data on the use of ezetimibe in children younger than 10 years are available. Information on the use of medications other than cholestyramine and ezetimibe in sitosterolemia is limited. In 2006, administration of ezetimibe added to cholestyramine was reported in a patient with sitosterolemia with remarkably positive results. [38]
Surgical Care
Ileal bypass has been performed in select cases to decrease the levels of plant sterols in the body.
Consultations
Consultations may include the following:
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Cardiologist - For assistance with treatment and evaluation of coronary artery disease
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Lipid disorder specialist - May assist with diagnosis and treatment
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Dietitian - To educate patient regarding low plant sterol diet
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Medical geneticist, metabolic disease specialist, or both - Helpful in establishing diagnosis, coordinating molecular testing of causative genes, providing potential genetic counseling, and implementing treatment (With identification of disease genes, prenatal counseling and diagnosis may become available.)
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Rheumatologist - Optional depending on if arthritic symptoms exist
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Hematologist - Optional depending on if hemolysis, anemia, thrombocytopenia, or hypersplenism exists
Diet
With the advent of treatment with ezetimibe, dietary therapy may not be needed.
If dietary therapy is indicated, a diet with the lowest possible amounts of plant sterols is advised. Guidelines are as follows:
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Eliminate all sources of vegetable fats.
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Avoid all plant foods high in fat, such as olives and avocados.
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Eliminate vegetable oils, shortening, and margarine.
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Eliminate nuts, seeds, and chocolate.
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Avoid shellfish.
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Cereal products without germ are allowed.
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Food derived from animal sources with cholesterol as the dominant sterol is allowed.
Diet is quite restrictive, but references for acceptable commercial products, possible menus, and recipes are available. [39, 40]
Long-Term Monitoring
Monitor plant sterol levels in plasma to assess treatment efficacy.
Further Inpatient Care
Inpatient care usually is not necessary in patients with sitosterolemia unless significant heart disease, hemolysis, or severe arthritis is present.
Transfer
Blood sterol analysis, which is the only diagnostic test for sitosterolemia, is a specialized test available in only a few laboratories. Transfer of the patient or a specimen may be warranted.
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Tuberous xanthomas. Courtesy of Duke University Medical Center.
