Summary
Usage The Friedewald formula allows clinicians to estimate LDL based on total serum cholesterol, HDL and triglyceride levels. However, this formula is known to be inaccurate at extremely high triglyceride (> 400 mg/dL) and total cholesterol levels (Cordova, 2004). Additionally, triglycerides should only be calculated when fasting.. Summary The Friedewald Formula provides an estimation of LDL cholesterol which can serve as a proxy for direct measure of serum cholesterol. A direct level of serum LDL should be measured if there is any question about accuracy. LDL cholesterol = total cholesterol - HDL - (triglycerides / 5) Classification of calculated LDL level according to the ATP III guidelines. LDL Level (mg/dL)Classification<100Optimal100-129Near optimal/above optimal130-159Borderline high160-189High≥ 190Very high Classification of triglyceride level according to the ATP III guidelines. Triglyceride Level (mg/dL)Classification< 150Normal150-199Borderline high200-499 High≥ 500Very high Classification of HDL level according to the ATP III guidelines. HDL Level (mg/dL)Classification< 40Low≥ 60High* *HDL ≥60 mg/dL counts as a "negative" risk factor; its presence removed one risk factor from the total count. Classification of total cholesterol level according to the ATP III guidelines. Total Cholesterol Level (mg/dL)Classification< 200Desirable200-239Borderline high≥ 240High Management Considerations The ATP III cholesterol guidelines suggests additional steps after determining lipoprotein levels. Identify presence of clinical atherosclerotic disease and major risk factors.Determine risk category.Initiate therapeutic lifestyle changes (TLC) if LDL is above goal.Consider adding drug therapy if LDL exceeds levels based on risk category.Identify metabolic syndrome and treat, if present, after 3 months of TLC.Treat elevated triglycerides. LDL targets (mg/dL)* "Very" high risk< 70Data may suggest there is little incremental benefit to this extreme, and high associated cost.High risk< 100Known CAD or other atherosclerotic disease, diabetes, etc.Moderate risk<130> 1 risk factor^Lower risk<1600-1 risk factors *From NCEP 2004 Guidelines^Risk Factors include:DiabetesCigarette smokingHTN (BP ≥ 140/90 or on antihypertensive medication)Low HDL cholesterol (<40 mg/dL)Family history of premature CAD (CAD in male first-degree relative, or father < 55 years, or female first-degree relative or mother <65 years).