To assess and monitor risk for coronary artery disease.
Serum (1 mL) collected in a red- or tiger-top tube. Plasma (1 mL) collected in a green-top (heparin) tube is also acceptable. It is important to use the same tube type when serial specimen collections are anticipated for consistency in testing.
|Risk||Conventional Units||SI Units (Conventional Units × 0.0259)|
|Children and adolescents (less than 20 yr)|
|Desirable||Less than 170 mg/dL||Less than 4.4 mmol/L|
|Borderline||170–199 mg/dL||4.4–5.2 mmol/L|
|High||Greater than 200 mg/dL||Greater than 5.2 mmol/L|
|Adults and older adults|
|Desirable||Less than 200 mg/dL||Less than 5.18 mmol/L|
|Borderline||200–239 mg/dL||5.18–6.19 mmol/L|
|High||Greater than 240 mg/dL||Greater than 6.22 mmol/L|
|Plasma values may be 10% lower than serum values.|
DescriptionCholesterol is a lipid needed to form cell membranes and a component of the materials that render the skin waterproof. It also helps form bile salts, adrenal corticosteroids, estrogen, and androgens. Cholesterol is obtained from the diet (exogenous cholesterol) and also synthesized in the body (endogenous cholesterol). Although most body cells can form some cholesterol, it is produced mainly by the liver and intestinal mucosa. Cholesterol is an integral component in cell membrane maintenance and hormone production. Very low cholesterol values, as are sometimes seen in critically ill patients, can be as life-threatening as very high levels.
According to the National Cholesterol Education Program, maintaining cholesterol levels less than 200 mg/dL significantly reduces the risk of coronary heart disease. Beyond the total cholesterol and high-density lipoprotein cholesterol (HDLC) values, other important risk factors must be considered. The Framingham algorithm can assist in estimating the risk of developing coronary artery disease (CAD) within a 10-yr period. Many myocardial infarctions occur even in patients whose cholesterol levels are considered to be within acceptable limits or who are in a moderate-risk category. The combination of risk factors and lipid values helps identify individuals at risk so that appropriate interventions can be taken. If the cholesterol level is greater than 200 mg/dL, repeat testing after a 12- to 24-hr fast is recommended. Another predictor of CAD is lipoprotein (a) or Lp(a). Lp(a) is considered an independent risk factor for CAD and cerebral infarction at levels greater than 30 mg/dL.
- Assist in determining risk of cardiovascular disease
- Assist in the diagnosis of nephrotic syndrome, hepatic disease, pancreatitis, and thyroid disorders
- Evaluate the response to dietary and drug therapy for hypercholesterolemia
- Investigate hypercholesterolemia in light of family history of cardiovascular disease
Although the exact pathophysiology is unknown, cholesterol is required for many functions at the cellular and organ level. Elevations of cholesterol are associated with conditions caused by an inherited defect in lipoprotein metabolism, liver disease, kidney disease, or a disorder of the endocrine system.
- Acute intermittent porphyria
- Anorexia nervosa
- Chronic renal failure
- Diabetes (with poor control)
- Diets high in cholesterol and fats
- Familial hyperlipoproteinemia
- Glycogen storage disease (von Gierke’s disease)
- Hypothyroidism (primary)
- Ischemic heart disease
- Nephrotic syndrome
- Pancreatic and prostatic malignancy
- Syndrome X (metabolic syndrome)
- Werner’s syndrome
Although the exact pathophysiology is unknown, cholesterol is required for many functions at the cellular and organ level. Decreases in cholesterol levels are associated with conditions caused by malnutrition, malabsorption, liver disease, and sudden increased utilization.
- Chronic myelocytic leukemia
- Chronic obstructive pulmonary disease
- Liver disease (severe)
- Malabsorption and malnutrition syndromes
- Pernicious anemia
- Polycythemia vera
- Severe illness
- Sideroblastic anemias
- Tangier disease
- Waldenström’s macroglobulinemia
- Drugs that may increase cholesterol levels include amiodarone, androgens, β-blockers, calcitriol, cortisone, cyclosporine, danazol, diclofenac, disulfiram, fluoxymesterone, glucogenic corticosteroids, ibuprofen, isotretinoin, levodopa, mepazine, methyclothiazide, miconazole (owing to castor oil vehicle, not the drug), nafarelin, nandrolone, some oral contraceptives, oxymetholone, phenobarbital, phenothiazine, prochlorperazine, sotalol, thiabendazole, thiouracil, tretinoin, and trifluoperazine.
- Drugs that may decrease cholesterol levels include acebutolol, amiloride, aminosalicylic acid, androsterone, ascorbic acid, asparaginase, atenolol, atorvastatin, beclobrate, bezafibrate, carbutamide, cerivastatin, cholestyramine, ciprofibrate, clofibrate, clonidine, colestipol, dextrothyroxine, doxazosin, enalapril, estrogens, fenfluramine, fenofibrate, fluvastatin, gemfibrozil, haloperidol, hormone replacement therapy, hydralazine, hydrochlorothiazide, interferon, isoniazid, kanamycin, ketoconazole, lincomycin, lisinopril, lovastatin, metformin, nafenopin, nandrolone, neomycin, niacin, nicotinic acid, nifedipine, oxandrolone, paromomycin, pravastatin, probucol, simvastatin, tamoxifen, terazosin, thyroxine, trazodone, triiodothyronine, ursodiol, valproic acid, and verapamil.
- Ingestion of alcohol 12 to 24 hr before the test can falsely elevate results.
- Ingestion of drugs that alter cholesterol levels within 12 hr of the test may give a false impression of cholesterol levels, unless the test is done to evaluate such effects.
- Positioning can affect results; lower levels are obtained if the specimen is from a patient who has been supine for 20 min.
- Failure to follow dietary restrictions before the procedure may cause the procedure to be canceled or repeated.
Nursing Implications Procedure
- Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
- Patient Teaching: Inform the patient this test can assist with evaluation of cholesterol level.
- Obtain a history of the patient’s complaints, including a list of known allergens, especially allergies or sensitivities to latex.
- Obtain a history of the patient’s cardiovascular, gastrointestinal, and hepatobiliary systems, as well as results of previously performed laboratory tests and diagnostic and surgical procedures. The presence of other risk factors, such as family history of heart disease, smoking, obesity, diet, lack of physical activity, hypertension, diabetes, previous myocardial infarction, and previous vascular disease, should be investigated.
- Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values).
- Review the procedure with the patient. Inform the patient that specimen collection takes approximately 5 to 10 min. Address concerns about pain and explain that there may be some discomfort during the venipuncture.
- Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
- Instruct the patient to withhold alcohol and drugs known to alter cholesterol levels for 12 to 24 hr before specimen collection, at the direction of the health-care provider (HCP).
- There are no fluid or medication restrictions unless by medical direction.
- Fasting 6 to 12 hr before specimen collection is required if triglyceride measurements are included; it is recommended if cholesterol levels alone are measured for screening. Protocols may vary among facilities.
- Ensure that the patient has complied with dietary restrictions and pretesting preparations; ensure that food has been restricted for at least 6 to 12 hr prior to the procedure if triglycerides are to be measured.
- If the patient has a history of allergic reaction to latex, avoid the use of equipment containing latex.
- Instruct the patient to cooperate fully and to follow directions. Direct the patient to breathe normally and to avoid unnecessary movement.
- Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient, and label the appropriate specimen container with the corresponding patient demographics, initials of the person collecting the specimen, date, and time of collection. Perform a venipuncture.
- Remove the needle and apply direct pressure with dry gauze to stop bleeding. Observe/assess venipuncture site for bleeding or hematoma formation and secure gauze with adhesive bandage.
- Promptly transport the specimen to the laboratory for processing and analysis.
- A report of the results will be made available to the requesting HCP, who will discuss the results with the patient.
- Instruct the patient to resume usual diet as directed by the HCP.
- Secondary causes for increased cholesterol levels should be ruled out before therapy to decrease levels is initiated by use of drugs.
- Nutritional Considerations: Increases in total cholesterol levels may be associated with CAD. Nutritional therapy is recommended for patients identified to be at high risk for developing CAD. If overweight, the patient should be encouraged to achieve a normal weight. The American Heart Association and National Heart, Lung, and Blood Institute (NHLBI) recommend nutritional therapy for individuals identified to be at high risk for developing CAD or individuals who have specific risk factors and/or existing medical conditions (e.g., elevated LDL cholesterol levels, other lipid disorders, insulin-dependent diabetes, insulin resistance, or metabolic syndrome). If overweight, the patient should be encouraged to achieve a normal weight. Guidelines for the Therapeutic Lifestyle Changes (TLC) diet are outlined in the Third Report of the Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III [ATP III]). The TLC diet emphasizes a reduction in foods high in saturated fats and cholesterol. Red meats, eggs, and dairy products are the major sources of saturated fats and cholesterol. If triglycerides also are elevated, the patient should be advised to eliminate or reduce alcohol and simple carbohydrates from the diet. The TLC approach also includes the use of plant stanols or sterols and increased dissolved fiber as an option for lowering LDL cholesterol levels; nutritional recommendations for daily total caloric intake; recommendations for allowable percentage of calories derived from fat (saturated and unsaturated), carbohydrates, protein, and cholesterol; as well as recommendations for daily expenditure of energy.
- Nutritional Considerations: Overweight patients with high blood pressure should be encouraged to achieve a normal weight. Other changeable risk factors warranting patient education include strategies to safely decrease sodium intake, increase physical activity, decrease alcohol consumption, eliminate tobacco use, and decrease cholesterol levels.
- Social and Cultural Considerations: Numerous studies point to the prevalence of excess body weight in American children and adolescents. Experts estimate that obesity is present in 25% of the population ages 6 to 11 yr. The medical, social, and emotional consequences of excess body weight are significant. Special attention should be given to instructing the child and caregiver regarding health risks and weight-control education.
- Recognize anxiety related to test results, and be supportive of fear of shortened life expectancy. Discuss the implications of abnormal test results on the patient’s lifestyle. Provide teaching and information regarding the clinical implications of the test results, as appropriate. Educate the patient regarding access to counseling services. Provide contact information, if desired, for the American Heart Association (www.americanheart.org) or the NHLBI (www.nhlbi.nih.gov).
- Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP. Answer any questions or address any concerns voiced by the patient or family.
- Depending on the results of this procedure, additional testing may be performed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.
- Related tests include antiarrhythmic drugs, apolipoprotein A and B, AST, ANP, blood gases, BNP, calcium, cholesterol (HDL and LDL), CT cardiac scoring, CRP, CK and isoenzymes, echocardiography, glucose, glycated hemoglobin, Holter monitor, homocysteine, ketones, LDH and isoenzymes, lipoprotein electrophoresis, MRI chest, magnesium, MI scan, myocardial perfusion heart scan, myoglobin, PET heart, potassium, triglycerides, troponin.
- Refer to the Cardiovascular, Gastrointestinal, and Hepatobiliary systems tables at the end of the book for related tests by body system.