endocrine and metabolic disorders
Hypolipidemia
Introduction
Hypolipidemia is a decrease in plasma lipoprotein caused by primary (genetic) or secondary factors. It is usually asymptomatic and diagnosed incidentally on routine lipid screening. Treatment of secondary hypolipidemia involves treating underlying disorders. Treatment of primary hypolipidemia is often unnecessary, but patients with some genetic disorders require high-dosevitamin Eand dietary supplementation of fats and other fat-soluble vitamins. (See also Overview of Lipid Metabolism .) Hypolipidemia is defined as a total cholesterol (TC)<120 mg/dL (<3.1 mmol/L) or low-density lipoprotein cholesterol (LDL-C)<50 mg/dL (<1.3 mmol/L). Causes may be primary (genetic) or secondary. Secondary causes are far more common than primary causes and include all of the following: Chronic infections (including Hepatitis C, Chronic ) and other inflammatory states Hematologic and other cancers Hyperthyroidism None Overview of Malabsorption None Overview of Undernutrition (including that accompanying chronic alcohol use) The unexpected finding of low cholesterol or low LDL-C in a patient not taking a lipid-lowering drug should prompt a diagnostic evaluation, including measurements of AST (aspartate aminotransferase), ALT (alanine aminotransferase), and thyroid-stimulating hormone; a negative evaluation suggests a possible primary cause. There are 3 primary disorders in which single or multiple genetic mutations result in underproduction or increased clearance of LDL: Abetalipoproteinemia Chylomicron retention disease Hypobetalipoproteinemia Loss-of-function mutations ofPCSK9(proprotein convertase subtilisin-like/kexin type 9) are another cause of low LDL levels. There are no adverse consequences and no treatment, 