Which conditions are included in the differential diagnoses of a depressed HDL-C level?

Updated: Jun 27, 2019
  • Author: Henry J Rohrs, III, MD; Chief Editor: Stuart Berger, MD  more...
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The differential diagnosis of a depressed HDL-C level includes familial disorders, genetic disorders, smoking, obesity, hypertriglyceridemia, renal failure, and drugs (eg, anabolic steroids, progestins, beta blockers, thiazides), with male sex and a sedentary lifestyle being additional risk factors for low HDL-C. In familial hypoalphalipoproteinemia (ie, low HDL-C) and Tangier disease, depressed apoprotein A-I levels are found. Other rare genetic causes of low HDL-C levels include fish-eye disease and lecithin-cholesterol acyl transferase (LCAT) deficiency. In fish-eye disease, patients have TG elevations to 250-300 mg/dL, severely depressed HDL-C levels, and corneal opacities. In LCAT deficiency, cholesterol esters cannot be formed; thus, cholesterol does not move into the core of the HDL particle disc.

Causes of acquired low LDL-C levels include malnutrition from starvation or malabsorption, hyperthyroidism, chronic anemia, severe hepatic dysfunction, and acute severe stress (eg, burns, trauma, myocardial infarction). Genetic forms of hypolipidemia are very rare but are potentially serious. Such conditions include abetalipoproteinemia (autosomal recessive), homozygous hypobetalipoproteinemia, heterozygous hypobetalipoproteinemia (with or without GI tract or neurologic symptoms), abetalipoproteinemia with normotriglyceridemia, and chylomicron retention disease. Low cholesterol levels secondary to deficiency of 7-dehydrocholesterol-δ-7 reductase are seen in Smith-Lemli-Opitz syndrome associated with mental retardation and ambiguous genitalia.

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