Lipid Tests Health Article

Preparation

Patients who are scheduled for a lipid profile test should fast (except for water) for 12 to 14 hours before the blood sample is drawn. If the patient's LDL cholesterol is to be measured, he or she should also avoid alcohol for 24 hours before the test. When possible, patients should also stop taking any medications that may affect the accuracy of the test results. These drugs include corticosteroids; estrogen or androgens; oral contraceptives; some diuretics; antipsychotic medications, including haloperidol; some antibiotics; and niacin. Antilipemics are drugs that lower the concentration of fatty substances in the blood. When these medications are taken by the patient, blood testing may be done frequently to evaluate liver function as well as lipid levels.

Aftercare

Aftercare following blood lipid tests includes routine care of the skin around the needle puncture. Most patients have no aftereffects, but some may have a small bruise or swelling. A washcloth soaked in warm water usually relieves any discomfort. In addition, the patient can resume taking any prescription medications that were discontinued before the test.

Care after amniocentesis requires that the clinician monitor the patient for any signs of infection or possible injury to the fetus. Some things to look for are fever, vaginal bleeding, or vaginal discharge. The patient may feel sick and there may be some cramping. She should be advised to rest and avoid strenuous activity. If the mother appears to be going into labor, she should be given supportive care. She may be given medications known as tocolytic agents to prevent the premature birth of the baby.

Risks

The primary risk to the patient from blood tests of lipid levels is a mild stinging or burning sensation during the venipuncture, with minor swelling or bruising afterward.

Although amniocentesis is much safer in the third trimester, and is less risky when it is performed with the guidance of ultrasound technology, does present a risk of miscarriage and fetal injury. The mother should be monitored for any signs of bleeding, infection, or impending labor.

Results

The normal values for serum lipids depend on the patient's age, sex, and race. Normal values for people in Western countries are usually given as 140–220 mg/dL for total cholesterol in adults, although as many as 5% of the population have a total cholesterol higher than 300 mg/dL. Among Asians, the figures are about 20% lower. As a rule, both total and LDL cholesterol levels rise as people get older. Normal values for HDL cholesterol are also age- and sex-dependent. The range for males between 20 and 29 years is approximately 30–63 mg/dL; for females of the same age group it is 33–83 mg/dL. Normal values for fasting triglycerides are also age- and sex-dependent. The reference range for adult males 20 to 29 years is 45–200 mg/dL; for females of the same age group it is 37–144 mg/dL. As with cholesterol, the normal range rises with age.

Since a person's diet and lifestyle affect normal values, which are determined by the interval between the 5th and 95th percentile of the group, it is more helpful to evaluate cholesterol and triglycerides from the perspective of desirable plasma levels. The desirable values defined by the Nation Cholesterol Education Program (NCEP) in 2001 are as follows:

• Total cholesterol: Less than 200 mg/dL; 200–239 mg/dL is considered borderline high and greater than 240 mg/dL is high.
• HDL cholesterol: Less than 40mg/dL is low.
• LDL cholesterol: Less than 100 mg/dL is optimal; near-optimal is 100–129 mg/dL; borderline high is 130-159 mg/dL; high is 160–189 mg/dL; and very high is any value over 190 mg/dL.
• Total cholesterol: HDL ratio: Under 4.0 in males; 3.8 in females.

Fetal lung maturity tests

Low levels of surfactant in amniotic fluid are denoted by an L/S ratio lower than 2.0 or a lecithin level lower than or equal to 0.10 mg/dL. Lung development can be delayed in premature births and in babies whose mothers have diabetes.

Patient education

Nurses should explain the results of abnormal blood lipid tests to patients and advise them on lifestyle changes. Patient education is important in fetal lung maturity testing. The situation faced by the expectant parents may be very critical; the more information they are given, the better choices they can make.