Definition
- A steroid, carried in the bloodstream as a lipoprotein. It is necessary for cell membrane functioning and as a precursor to bile acids, progesterone, vitamin D, estrogens, glucocorticoids, and mineralocorticoids.
- Normal range: see Table 16.22.
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TABLE 16 " “22Initial Classification Based on Total Cholesterol and HDL CholesterolView LargeTABLE 16 " “22Initial Classification Based on Total Cholesterol and HDL Cholesterol Total Cholesterol Level Category <200 mg/dL Desirable level that puts a person at a lower risk of coronary heart disease. A cholesterol level of ≥200 mg/dL raises the risk 200 " “239 mg/dL Borderline high ≥240 mg/dL High blood cholesterol. A person with this level has more than twice the risk of CHD as someone whose cholesterol is <200 mg/dL
Use
- Assessment of risk of heart disease and atherosclerosis
- Ordered in combination with HDL, LDL, and triglycerides as a lipid profile
Interpretation
Increased In
- Pregnancy
- Drugs: beta blockers, anabolic steroids, vitamin D, oral contraceptives, and epinephrine
- Obesity
- Smoking
- Alcohol
- Diet high in cholesterol and fats
- Renal failure
- Hypothyroidism
- Glycogen storage disease (i.e., von Gierke and Werner diseases)
- Familial hypercholesterolemia
- DM
- Biliary cirrhosis, hepatocellular disease
- Hyperlipoproteinemia types I, IV, V
- Prostate and pancreatic neoplasms
Decreased In
- Acute illness such as a heart attack
- Malnutrition
- Liver disease
- Myeloproliferative diseases
- Chronic anemias
- Infection
- Hyperthyroidism
- Stress
- Primary lipoproteinemias
- Tangier disease (familial alphalipoprotein deficiency)
Limitations
- Intraindividual variation may be up to 10%.
- Seasonal variation is 8% higher in the winter than in summer.
- Positional variation is 5% and 10 " “15% lower when phlebotomized sitting or recumbent, respectively, as opposed to standing.
- Other factors that may also increase cholesterol include cigarette smoking, age, hypertension, family history of premature heart disease, preexisting heart disease, and DM.
Suggested Reading
1American Heart Association. Cholesterol. http://www.heart.org/HEARTORG/Conditions/Cholesterol/CholestrolATH_UCM_001089_SubHomePage.jsp. Accessed November 18, 2010.