Triglycerides account for >90% of dietary fat intake and comprise 95% of fat stored in tissues. Because they are insoluble in water, they are the main plasma glycerol ester. Normally stored in adipose tissue as glycerol, fatty acids, and monoglycerides, the liver reconverts these to triglycerides. Of the total, 80% of triglycerides are in VLDL, and 15% are in LDL.
This test evaluates suspected atherosclerosis and measures the body’s ability to metabolize fat. Elevated triglycerides, together with elevated cholesterol, are atherosclerotic disease risk factors. Because cholesterol and triglycerides can vary independent of each other, measurement of both values is more meaningful. Triglyceride level is needed to calculate the LDL-C and is also used to evaluate turbid samples of blood and plasma.
Desirable: <150 mg/dL or <1.70 mmol/L
Borderline high: 150–199 mg/dL or 1.70–2.25 mmol/L
High: 200–499 mg/dL or 2.26–5.64 mmol/L
Very high: ≥500 mg/dL or ≥5.65 mmol/L
Table 6.15 lists specific values for children.
Clinical Alert
Critical ValueValues >500 mg/dL (>5.6 mmol/L) indicate hypertriglyceridemia in the presence of diagnosed pancreatitis.
Obtain a 5-mL venous blood sample. Serum is used, but many laboratories use EDTA anticoagulant plasma levels, which are slightly lower. Fasting for 12–14 hours is required.
Observe standard precautions. Do not use glycerinated tubes. Label the specimen with the patient’s name, date and time of collection, and test(s) ordered. Place the specimen in a biohazard bag.
Increased triglycerides occur with the following conditions:
Hyperlipoproteinemia types I, IIb, III, IV, and V
Liver disease, alcoholism (can be extremely high with alcoholism)
Nephrotic syndrome, renal disease
Hypothyroidism
Poorly controlled diabetes
Pancreatitis
Glycogen storage disease (von Gierke disease)
MI (elevated levels may persist for several months)
Gout
Werner syndrome (rare autosomal recessive progeroid syndrome, premature aging)
Down syndrome
Anorexia nervosa
Decreased triglyceride levels occur with the following conditions:
Congenital α-β-lipoproteinemia
Malnutrition, malabsorption syndromes
Hyperthyroidism, hyperparathyroidism
Brain infarction
COPD
Certain levels of triglycerides are associated with certain disorders:
Desirable: 150 mg/dL (<1.70 mmol/L)—not associated with a disease state
Borderline: 150–500 mg/dL (1.70–5.65 mmol/L)—associated with peripheral vascular disease and may be a marker for genetic forms of hyperlipoproteinemias that need specific therapy
Hypertriglyceridemia
>500 mg/dL (>5.6 mmol/L)—associated with risk for pancreatitis
>1000 mg/dL (>11.3 mmol/L)—associated with type I or V hyperlipidemia and substantial risk for pancreatitis
>5000 mg/dL (>56.5 mmol/L)—associated with eruptive xanthoma, corneal arcus, lipemia retinalis, and enlarged liver and spleen
Clinical Alert
Chylomicronemia, although associated with pancreatitis, is not accompanied by increased atherogenesis. Chylomicrons are not seen in normal fasting serum but instead are found as exogenous triglycerides in healthy persons after a fatty meal has been eaten. After refrigeration, chylomicrons float to the surface of a blood sample
Pretest Patient Care
Explain test purpose and procedure. Fasting for at least 12 hours overnight is required, but water may be ingested.
Ask the patient to follow a normal diet for 1 week before the test. No alcohol is permitted for at least 24–48 hours before testing.
Follow guidelines in Chapter 1 for safe, effective, informed pretest care.
Posttest Patient Care
Review test results; report and record findings. Modify the nursing care plan as needed. Weight reduction, a low-fat diet, and an exercise program can reduce high triglyceride levels.
Advise that triglycerides are not a strong predictor of CAD and, as such, are not an independent risk factor if <250 mg/dL (<2.8 mmol/L). However, increased levels may increase cardiovascular disease risk.
Follow guidelines in Chapter 1 for safe, effective, informed posttest care.
A transient increase occurs following a heavy meal or alcohol ingestion.
Transient decrease occurs after strenuous exercise, permanent decrease with weight loss.
Increased values are associated with pregnancy and oral contraceptive use.
Values may be increased in acute illness, colds, or flu.
Many drugs cause increases or decreases (see Appendix E).
Values are increased with obesity, physical inactivity, and smoking.