cholesterol
المؤلف:
Kathleen Deska Pagana, Timothy J. Pagana, Theresa Noel Pagana.
المصدر:
Mosbys diagnostic and laboratory test reference
الجزء والصفحة:
15th edition , p237-239
2025-11-09
54
Type of test Blood
Normal findings
Adult/elderly: < 200 mg/dL or < 5.2 mmol/L (SI units)
Child: 120-200 mg/dL Infant: 70-175 mg/dL
Newborn: 53-135 mg/dL
Test explanation and related physiology
Cholesterol is the main lipid associated with arteriosclerotic vascular disease. Nearly 75% of the cholesterol is bound to LDLs and 25% is bound to HDLs. Therefore cholesterol is the main component of LDLs and only a minimal component of HDLs and very low-density lipoproteins. LDLs are most directly associated with increased risk of coronary heart disease (CHD).
The purpose of cholesterol testing is to identify patients at risk for arteriosclerotic heart disease. Cholesterol testing is usually done as a part of lipid profile testing, which also evaluates lipoproteins and triglycerides, because by itself cholesterol is not a totally accurate predictor of heart disease.
Because the liver is required to make cholesterol, low serum cholesterol levels are indicative of severe liver diseases. Furthermore, because our main source of cholesterol is our diet, malnutrition is also associated with low cholesterol levels. Certain illnesses can affect cholesterol levels. For example, patients with an acute myocardial infarction may have as much as a 50% reduction in cholesterol level for as many as 6 to 8 weeks.
The goal for high-risk patients (those with known coronary artery disease or more than two risk factors) is LDL less than 70 mg/dL. Many prospective studies have shown that high serum concentrations of LDL-C are a major risk factor for CHD. Moreover, lowering of LDL-C levels will reduce the risk for major coronary events. The cholesterol-to-HDL ratio has been used to assess the risk of CHD (Table 1). Familial hyperlipidemias and hyperlipoproteinemias are often associated with high cholesterol.
Table1. Cholesterol-to-HDL ratio as an indicator of risk of coronary heart disease
Interfering factors
• Pregnancy is usually associated with elevated cholesterol levels.
• Oophorectomy increases levels.
* Drugs that may cause increased levels include adrenocorticotropic hormone, anabolic steroids, beta-adrenergic blocking agents, corticosteroids, cyclosporine, epinephrine, oral contraceptives, phenytoin (Dilantin), sulfonamides, thiazide diuretics, and vitamin D.
* Drugs that may cause decreased levels include allopurinol, androgens, bile salt-binding agents, captopril, chlorpropamide, clofibrate, colchicine, colestipol, erythromycin, isoniazid, liothyronine (Cytomel), monoamine oxidase inhibitors, neomycin (oral), niacin, nitrates, and statins.
Procedure and patient care
• See inside front cover for Routine Blood Testing.
• Fasting: yes
• Blood tube commonly used: red
* Instruct the patient to fast 12 to 14 hours after eating a low fat diet before testing. Only water is permitted. Food can elevate triglyceride levels.
* Inform the patient that dietary intake at least 2 weeks before testing will affect results.
* Tell the patient that no alcohol should be consumed 24 hours before the test.
• The fingerstick method is often used in mass screening.
* Instruct patients with high levels regarding a low-cholesterol diet, exercise, and appropriate body weight.
Abnormal findings
Increased levels
- Hypercholesterolemia
- Hyperlipidemia
- Hypothyroidism
- Uncontrolled diabetes mellitus
- Nephrotic syndrome
- Pregnancy
- High-cholesterol diet
- Xanthomatosis
- Hypertension
- Myocardial infarction
-Atherosclerosis
- Biliary cirrhosis
-Stress
- Nephrosis
Decreased levels
- Malabsorption
- Malnutrition
- Hyperthyroidism
-Cholesterol-lowering medication
- Pernicious anemia
- Hemolytic anemia
- Sepsis
- Stress
- Liver disease
- Acute myocardial infarction
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