Lipid Panel Interpretation Flashcards

A patient's lipid panel shows LDL-C 160 mg/dL, HDL-C 38 mg/dL, TG 280 mg/dL, and total cholesterol 254 mg/dL. The Friedewald equation was used. Why might the calculated LDL-C be unreliable?

Answer: Triglycerides exceed 200 mg/dL, reducing accuracy

The Friedewald equation becomes unreliable when triglycerides exceed 200 mg/dL and is invalid above 400 mg/dL because VLDL-C estimation (TG/5) is inaccurate at elevated TG levels.

Which lipoprotein fraction is most directly measured in a standard fasting lipid panel rather than calculated?

Answer: HDL cholesterol

HDL cholesterol is directly measured via precipitation or homogeneous assay methods, whereas LDL-C and VLDL-C are typically calculated from measured values.

A non-fasting lipid panel is acceptable for initial cardiovascular risk screening primarily because which value is least affected by a recent meal?

Answer: HDL-C

HDL-C remains relatively stable after meals and is the least postprandially affected major lipid fraction, making non-fasting panels useful for initial screening.

A patient has TG of 650 mg/dL. Which parameter on the lipid panel can still be reliably used to guide statin therapy initiation?

Answer: Non-HDL cholesterol

Non-HDL cholesterol (total cholesterol minus HDL-C) is directly calculated from measured values and remains valid regardless of triglyceride levels, making it the preferred treatment target when TG exceed 400 mg/dL.

In a patient with familial hypercholesterolemia, which lipid panel finding is most characteristic?

Answer: Severely elevated LDL-C with relatively normal triglycerides and HDL-C

Familial hypercholesterolemia is characterized by dramatically elevated LDL-C (often >190 mg/dL in adults) due to defective LDL receptor function, with triglycerides and HDL-C typically in the normal range.

A lipid panel shows TC 180 mg/dL, HDL-C 55 mg/dL, TG 90 mg/dL, and LDL-C 107 mg/dL. What is the calculated non-HDL cholesterol?

Answer: 125 mg/dL

Non-HDL cholesterol = Total cholesterol − HDL-C = 180 − 55 = 125 mg/dL, encompassing all atherogenic lipoproteins including LDL, VLDL, IDL, and Lp(a).

Which lipid panel result pattern is most consistent with type III hyperlipoproteinemia (familial dysbetalipoproteinemia)?

Answer: Near-equal elevations of both cholesterol and triglycerides with elevated remnant lipoproteins

Type III hyperlipoproteinemia (apoE2/E2 genotype) is characterized by roughly equal elevations of cholesterol and triglycerides (both often 250–500 mg/dL) due to accumulation of IDL and chylomicron remnants.