Lipid Profile — Purpose, Procedure & Normal Values | MyMedicPlus

A lipid profile — also called a lipid panel, fasting lipid panel, or cholesterol test — is a blood test that quantifies the major circulating fat (lipid) fractions in the bloodstream, providing essential information for cardiovascular risk assessment and management. The standard panel reports four components: total cholesterol (the sum of all cholesterol-containing lipoprotein fractions); LDL cholesterol (low-density lipoprotein — the primary atherogenic fraction that deposits cholesterol into arterial plaques, driving atherosclerosis and coronary artery disease); HDL cholesterol (high-density lipoprotein — the protective fraction that mediates reverse cholesterol transport from arterial walls back to the liver for excretion); and triglycerides (blood-borne fatty acids derived from dietary fats and hepatic lipogenesis, transported in VLDL). From these four values, additional calculated markers are derived: non-HDL cholesterol (total cholesterol minus HDL — a superior cardiovascular risk predictor than LDL alone because it captures VLDL and IDL), total cholesterol/HDL ratio, and LDL/HDL ratio. Advanced lipid testing may add apolipoprotein B (ApoB — the primary protein of all atherogenic lipoproteins), apolipoprotein A-I, Lp(a) (lipoprotein(a) — a genetically determined independent cardiovascular risk factor), and lipoprotein particle number and size. The lipid profile is the primary screening and monitoring tool for dyslipidaemia and is ordered by cardiologists, endocrinologists, and general practitioners across all healthcare settings.

A lipid profile is ordered as part of primary cardiovascular risk assessment in all adults from age 20 onwards — more frequently in those with risk factors including family history of premature coronary artery disease, obesity, diabetes mellitus, hypertension, tobacco use, chronic kidney disease, inflammatory conditions (rheumatoid arthritis, psoriasis, HIV), and hypothyroidism. It guides initiation and titration of lipid-lowering pharmacotherapy — statins (atorvastatin, rosuvastatin), ezetimibe, PCSK9 inhibitors (evolocumab, alirocumab), bempedoic acid, and inclisiran — and monitors treatment response, typically at 4–12 weeks after starting or changing therapy. It screens for familial hypercholesterolaemia (FH) — an autosomal dominant disorder causing LDL above 190 mg/dL, affecting 1 in 250 people and dramatically increasing lifetime cardiovascular risk. Secondary dyslipidaemia is investigated by identifying elevated triglycerides in untreated or poorly controlled diabetes, hypothyroidism, liver disease, nephrotic syndrome, and excessive alcohol intake, all of which produce characteristic lipid abnormalities requiring treatment of the primary cause. Repeat testing is performed every 5 years in low-risk individuals with normal baseline values, annually in patients on lipid-lowering treatment, and after any significant lifestyle change.

For the most accurate measurement of triglycerides and calculated LDL, fast for 9–12 hours before the blood draw — water and essential medications are fully permitted. Non-fasting lipid profiles are now accepted by major European and North American guidelines for primary cardiovascular risk screening (total cholesterol, HDL, and non-HDL cholesterol are minimally affected by food intake), but fasting samples remain the standard for monitoring patients on treatment, assessing hypertriglyceridaemia, or calculating LDL using the Friedewald equation. Avoid alcohol for at least 24–48 hours before the test, as alcohol intake significantly raises triglycerides and can cause falsely elevated readings. Refrain from strenuous aerobic exercise for at least 12 hours before sampling, as exercise temporarily increases HDL and can alter the lipid profile. Inform your doctor of all current medications — statins, fibrates, and niacin should be taken as usual unless specifically instructed otherwise. Do not alter your usual diet in the days before the test — the result should reflect your habitual eating pattern rather than a temporarily improved diet.

A phlebotomist applies a tourniquet to your upper arm, cleans the antecubital fossa with an antiseptic swab, and inserts a sterile needle into a forearm vein to collect 3–5 mL of blood into a serum separator tube (gold or red-top) or a lithium heparin (green-top) tube. The tourniquet is released immediately after needle insertion to prevent haemoconcentration, which can affect measured cholesterol values. The tube is transported to the biochemistry laboratory where the serum is separated by centrifugation. Total cholesterol, HDL cholesterol, and triglycerides are measured directly using enzymatic colorimetric assays on an automated chemistry analyser. LDL cholesterol is calculated using the Friedewald equation: LDL = Total Cholesterol − HDL − (Triglycerides ÷ 5) (in mg/dL), which is valid only when triglycerides are below 400 mg/dL. When triglycerides exceed 400 mg/dL or when high precision is required (e.g., familial hypercholesterolaemia management), direct LDL measurement by homogeneous enzymatic assay is performed instead. Non-HDL cholesterol is automatically calculated. Results are typically available within 4–24 hours.

Adult reference ranges and risk categories: Total cholesterol — Desirable <200 mg/dL (<5.2 mmol/L); Borderline high 200–239 mg/dL; High ≥240 mg/dL (≥6.2 mmol/L). LDL cholesterol — Optimal <100 mg/dL (<2.6 mmol/L) for most adults; Near-optimal 100–129 mg/dL; Borderline high 130–159 mg/dL; High 160–189 mg/dL; Very high ≥190 mg/dL (suggests familial hypercholesterolaemia). For patients with established cardiovascular disease or very high risk (diabetes with organ damage, CKD, familial hypercholesterolaemia), LDL targets are more stringent: <70 mg/dL (ESC guidelines) or <55 mg/dL for very-high-risk patients. HDL cholesterol — Low cardiovascular risk: >60 mg/dL (>1.55 mmol/L); Average: men 40–59, women 50–59 mg/dL; Cardiovascular risk factor: <40 mg/dL in men, <50 mg/dL in women (<1.0 and <1.3 mmol/L respectively). Triglycerides — Normal <150 mg/dL (<1.7 mmol/L); Borderline high 150–199 mg/dL; High 200–499 mg/dL (significantly increases risk of pancreatitis at sustained levels >500 mg/dL); Very high ≥500 mg/dL (>5.6 mmol/L) — acute pancreatitis risk requires urgent triglyceride-lowering treatment with fibrates. Non-HDL cholesterol targets mirror LDL targets plus 30 mg/dL. Results must be interpreted using a validated 10-year cardiovascular risk calculator (ACC/AHA Pooled Cohort Equations, SCORE2, QRISK3) rather than treating individual lipid values in isolation.

The blood draw is extremely safe with minimal risk — minor bruising, soreness, or a small haematoma at the venepuncture site are the only common side effects, occurring in fewer than 5% of draws and resolving within 1–2 days. A significant analytical limitation is that LDL calculated using the Friedewald equation becomes unreliable and underestimates true LDL when triglycerides exceed 400 mg/dL — direct LDL measurement or the Sampson/Martin-Hopkins equation should be used in this situation. Lipid values are biologically variable and influenced by multiple factors: total cholesterol fluctuates by approximately 6–11% between measurements on different days (biological variation), acute illness and hospitalisation transiently decrease LDL by 10–20% (making lipid testing during hospital admission unreliable), pregnancy raises total cholesterol and triglycerides substantially, and thyroid status profoundly affects LDL (hypothyroidism doubles LDL in some patients). A single lipid panel should be interpreted alongside the patient's overall cardiovascular risk profile rather than as an isolated number — a patient with an LDL of 160 mg/dL who is a 35-year-old female non-smoker with no other risk factors has a very different absolute risk from a 65-year-old male smoker with hypertension and diabetes with the same LDL level. Lp(a), a heritable atherogenic lipoprotein not captured in a standard panel, is an independent cardiovascular risk factor affecting up to 20% of the population; its measurement is recommended at least once in patients with unexplained premature atherosclerosis or strong family history of cardiovascular disease.