Dyslipidemia is defined as elevated total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), triglycerides (TG), or low high-density lipoprotein cholesterol (HDL-C). LDL-C incites the atherosclerotic inflammatory response promoting unstable lesions concentrated with lipid-laden macrophages. The degree of LDL elevation is proportionally linked with risk of developing atherosclerotic cardiovascular disease (ASCVD; 1 mg/dL:1% change). Elevated TG has indirect atherosclerotic effects from procoagulant properties and an adverse impact on endothelial function. In contrast, HDL-C is an inverse predictor for ASCVD risk (1 mg/dL:2% change) due to reverse cholesterol transport (delivering cholesterol from the cell wall to the liver for disposal). Additionally, HDL-C inhibits LDL-C oxidation and platelet aggregation and activation.
Dyslipidemia is a risk factor for clinical ASCVD, defined as coronary heart disease (CHD), cerebrovascular disease, or peripheral artery disease. Dyslipidemia is asymptomatic until vascular disease develops. Patients may present with pain or cramping with walking, cold extremities, shortness of breath, chest pain, sweating, xanthomas, difficulty with speech or movement, and sudden death. Severe hypertriglyceridemia (TG >1000 mg/dL) can lead to abdominal pain, nausea, vomiting, and other symptoms of pancreatitis.
For adults 20 years of age or older a lipid profile is recommended once every 5 years. The National Cholesterol Education Program (NCEP) ATP III classifies optimal and abnormal findings (Table 5-1). A fasting lipid profile is no longer required, however, a follow-up fasting lipid panel (FLP) is required for TC 400 or more. The LDL-C can be measured directly or calculated using the Friedewald equation (LDL-C = TC − HDL-C − TG/5). The calculation is less accurate when TG are more than 200 and inaccurate more than 400 mg/dL.
TABLE 5-1Classification of Total-, LDL-, HDL-C and TG ||Download (.pdf) TABLE 5-1 Classification of Total-, LDL-, HDL-C and TG
|Total cholesterol || |
|<200 mg/dL ||Desirable |
|200-239 mg/dL ||Borderline high |
|≥240 mg/dL ||High |
|LDL cholesterol || |
|<100 mg/dL ||Optimal |
|100-129 mg/dL ||Near or above optimal |
|130-159 mg/dL ||Borderline high |
|160-189 mg/dL ||High |
|≥190 mg/dL ||Very high |
|HDL cholesterol || |
|<40 mg/dL ||Low |
|≥60 mg/dL ||High |
|Triglycerides || |
|<150 mg/dL ||Normal |
|150-199 mg/dL ||Borderline high |
|200-499 mg/dL ||High |
|≥500 mg/dL ||Very high |
Secondary causes of dyslipidemia should be considered, such as obesity, obstructive liver disease, Cushing syndrome, tobacco use, alcohol overuse, hypothyroidism, anorexia nervosa, nephrotic syndrome, and undiagnosed or uncontrolled diabetes. TG levels can be lowered by improving glucose control. Many medications also increase cholesterol (eg, β-blockers, estrogens, androgens, thiazide diuretics, glucocorticoids, isotretinoin, protease inhibitors, mirtazapine, sirolimus, and cyclosporine). Conversely, acutely ill patients or those with recent cerebrovascular events may have significant drops in LDL-C within 24 to 48 hours of the event and falsely low levels for weeks.
Dyslipidemia is associated with sedentary lifestyle, poor dietary choices, and obesity. Therapeutic lifestyle changes are ...