Appendix
← Clinical Reader
Cardiology

Sitosterolemia (Phytosterolemia)

Sitosterolemia, increasingly called Phytosterolemia or Xenosterolemia, is an inherited condition that can lead to premature heart disease and other complications. It is characterized by excess accumulation of plant sterols in the blood. Once clinically recognized, it can be diagnosed with laboratory testing and treated with a combination of medications and lifestyle modification. Objectives: Outline the etiology of sitosterolemia. Review clinical signs which can help physicians identify sitoster

v1 · Reviewed Nov 7, 2026 by Automated Clinical Reviewer (Strict Verbatim v1)
  • Sitosterolemia, increasingly called Phytosterolemia or Xenosterolemia, is an inherited condition that can lead to premature heart disease and other complications.
  • Patients can develop severe coronary artery disease, myocardial infarction, and other complications quite early in life if this condition is left untreated.
  • Delayed diagnosis can mean that patients may not be diagnosed until after suffering a cardiac event.
  • Untreated sitosterolemia can lead to premature coronary artery disease and death; given that the disease onsets early in life, timely diagnosis is required to prevent atherosclerosis.
  • Laboratory evaluation is required to make the diagnosis of sitosterolemia.
  • A serum plant sterol level is the standard method of diagnosing sitosterolemia.
  • This test is generally a panel that looks at the levels of sitosterol, campesterol, and stigmasterol.
  • Patients with this condition will have over 30 times the level of plant sterols in their blood than healthy patients.
  • For affected individuals, serum levels are often in the range of 10 to 65 mg/dL depending on the severity of the disease.
  • Generally, elevated serum levels may be considered diagnostic depending on the clinical scenario, but genetic testing can be done for confirmation.
  • Specifically, pathogenic variants in ABCG5 or ABCG8 are identified on genetic testing.
  • A complete blood count (CBC) and hemolysis diagnostic evaluation are generally sufficient to diagnose this.
  • Given the major association of sitosterolemia with premature atherosclerosis and cardiac valvular disease, it is generally reasonable to pursue diagnostic evaluation in the form of coronary imaging with computed tomography (CT), calcium scoring, and echocardiography.
  • The first step in treatment is significant dietary modifications.
  • This includes a major reduction in the intake of plant sterols and shellfish sterols.
  • Common examples include vegetable oils, nuts, and avocados.
  • Medications are generally required to fully control the chronic disease process of sitosterolemia.
ezetimibe
Not specified in source
Adult
10 mg per day
Renal
Not specified in source
Duration
Not specified in source
  • Other medication options include bile-acid binding resins such as cholestyramine.
  • However, this would only be used in conjunction with ezetimibe.
  • Prior to the approval of ezetimibe, surgical intervention with an ileal bypass was reserved for severe cases.
  • Statin therapy is not directly indicated for the treatment of sitosterolemia.
  • Likely, it would be prescribed for affected patients given its cardioprotective effect in the setting of atherosclerosis.
  • However, it would not lower plant sterol serum levels, and hence statin therapy alone is not an appropriate treatment for sitosterolemia.
  • Patients who have already developed heart disease should be concurrently managed with standard of care guidelines in addition to therapy for sitosterolemia.
  • Patients often experience a measurable reduction in serum sterol levels and cholesterol levels following the dietary intervention.
  • A serum plant sterol level is the standard method of diagnosing sitosterolemia.
  • Absolute concentrations of sitosterol range depending on laboratory, but a level of sitosterol > 7 mg/L would be at the 99th percentile.
  • Those with total loss of function of ABCG5 or G8 (homozygous phytosterolemia) have 99.9th percentile levels of > 20-30 mg/L or higher.
  • Lesser concentrations are usually partial ABCG5 or G8 loss of function.
  • A complete blood count (CBC) and hemolysis diagnostic evaluation are generally sufficient to diagnose this.
  • Patients may also have liver disease with an unknown etiology which may present as transaminitis with a negative comprehensive diagnostic workup.
  • Atherosclerosis and coronary artery disease
  • Myocardial infarction
  • Aortic stenosis
  • Premature cardiac death
  • Hemolytic anemia
  • Thrombocytopenia
  • Splenomegaly
  • Liver disease and cirrhosis
  • Arthritis and arthralgia
  • review
    Sitosterolemia (Phytosterolemia). StatPearls [Internet] — Khashayar Farzam, Ryan T. Morgan — StatPearls Publishing, 2023

Decision support only. Verify against local protocols and current labeling. Source: www.ncbi.nlm.nih.gov