Lipid Panel

Per 2018 ACC/AHA and European guidelines, a non-fasting lipid panel is acceptable for initial screening. Non-fasting triglycerides may be 20-30 mg/dL higher. Fasting (9-12 hours) is preferred when: triglycerides are >400, evaluating for familial hypertriglyceridemia, or when a calculated LDL is needed (Friedewald equation is unreliable with TG >400). Direct LDL measurement does not require fasting.

The Friedewald equation: LDL = Total cholesterol - HDL - (Triglycerides/5). This is inaccurate when TG >400 mg/dL, in non-fasting samples with high TG, and at very low LDL levels (<70). The Martin-Hopkins equation is more accurate at low LDL and moderate TG levels and is now used by many labs. Direct LDL measurement bypasses these limitations but is more expensive.

Before starting lipid therapy, rule out secondary causes: Hypothyroidism (check TSH — elevates LDL and TG), Diabetes (elevates TG, lowers HDL), Nephrotic syndrome (markedly elevated TC and LDL), CKD (elevated TG), Obstructive liver disease (elevated TC), Medications (thiazides, beta-blockers, steroids, retinoids, protease inhibitors, oral estrogens), Alcohol (elevates TG), Obesity/metabolic syndrome (elevated TG, low HDL).