What is sitosterolemia (phytosterolemia)?

Updated: May 24, 2019
  • Author: Robert D Steiner, MD; Chief Editor: Luis O Rohena, MD, MS, FAAP, FACMG  more...
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Sitosterolemia, also known as phytosterolemia, is a rare inherited plant sterol storage disease. Bhattacharyya and Connor first described this disease in 1974. [1, 2] The original report detailed 2 sisters who presented with extensive tendon xanthomas but normal plasma cholesterol levels. Subsequently, they were found to have significantly elevated plasma levels of plant sterols in the form of beta-sitosterol, campesterol, and stigmasterol.

Sitosterolemia is characterized by tendon and tuberous xanthomas and by a strong propensity toward premature coronary atherosclerosis. [3, 4]

See the image below.

Tuberous xanthomas. Courtesy of Duke University Me Tuberous xanthomas. Courtesy of Duke University Medical Center.

Significant increases of plant sterols (ie, phytosterols) are found in blood and various tissues. Arteries and xanthomas in patients with sitosterolemia contain increased amounts of these sterols, particularly sitosterol, stigmasterol, campesterol, and their 5-alpha derivatives.

Untreated, the condition causes a significant increase in morbidity and mortality. Coronary heart disease and its inherent health consequences are the primary causes of illness and premature death in untreated patients. With treatment, cholesterol levels can normalize, and xanthomas can completely regress.

A clue to sitosterolemia diagnosis in a patient with highly elevated plasma cholesterol level is parents with normal cholesterol levels.

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