High-risk persons: Lipoprotein measurement is recommended as a guide to clinical management. More frequent measurements are required for persons with multiple risk factors or, in those with 0–1 risk factors, if the LDL level is only slightly below the goal level.
Apolipoprotein (LpA): Elevated in the presence of concomitant hypercholesterolemia or hypoalphalipoproteinemia—may aid in risk assessment for CHD.
Lipoprotein electrophoresis: Shows a specific abnormal pattern in <2% of Americans; may be indicated if serum TG >300 mg/dL; fasting serum is lipemic; or if significant hyperglycemia, impaired glucose tolerance, or glycosuria is present. There is increased serum uric acid >8.5 mg/dL and/or strong family history of premature CHD.
Molecular tests: Pharmacogenomic studies have shown a genetic predisposition for individuals to develop heart disease.
Considerations:
If lipid screen is normal, further testing should be performed with consideration paid to the measurement of Lp(a) and apolipoproteins B and A-I. A standard serum lipid profile consists of total cholesterol, TG, and HDL-cholesterol.
Measure serum TC, HDL cholesterol, and TG after a 12- to 13-hour fast to minimize the influence of postprandial hyperlipidemia (total and HDL cholesterol can be measured in fasting or nonfasting individuals because the difference is clinically insignificant). Average results of two or three tests; if a difference of ≥30 mg/dL appears, repeat tests 1–8 weeks apart and average the results of three tests.
Use TC for initial case finding and classification and monitoring of diet therapy. Do not use age- or sex-specific cholesterol values as decision levels.
Consider values in association with clinical risk factors (e.g., age, gender, obesity, smoking, hypertension, and family history).
DISORDERS OF LIPID METABOLISM
ACID LIPASE DEFICIENCIES
Definition
Acid lipase deficiencies are characterized by the inability to hydrolyze lysosomal TG and cholesteryl esters.
Laboratory Findings
