A 52-year-old man with a 10-year history of type 2 diabetes and hypertension presents to the outpatient clinic. His lipid panel shows total cholesterol 285 mg/dL, LDL-C 180 mg/dL, HDL-C 35 mg/dL, and triglycerides 320 mg/dL. He is currently on metformin and amlodipine. His 10-year cardiovascular risk is estimated at 18%. Physical examination reveals xanthomas on the Achilles tendon and dorsal hands. What is the most appropriate next step in management?

Explanation

## Clinical Context This patient presents with: - Markedly elevated LDL-C (180 mg/dL) despite lifestyle factors - Tendon xanthomas (pathognomonic for familial hypercholesterolaemia) - Early-onset cardiovascular risk (age 52 with metabolic syndrome) - Premature atherosclerotic disease risk ## Diagnosis: Familial Hypercholesterolaemia (FH) **Key Point:** Tendon xanthomas are a clinical hallmark of heterozygous familial hypercholesterolaemia, caused by mutations in the LDL receptor gene, apolipoprotein B gene, or PCSK9 gene. These patients have defective or absent LDL receptors, leading to impaired hepatic uptake of LDL and severe hypercholesterolaemia. ## Management Algorithm ```mermaid flowchart TD A[Suspected FH: Xanthomas + Severe Hypercholesterolaemia]:::outcome --> B{Genetic confirmation needed?}:::decision B -->|Yes| C[Refer for genetic testing]:::action C --> D[Start high-intensity statin]:::action D --> E[Add ezetimibe if LDL goal not met]:::action E --> F[Consider PCSK9 inhibitor if LDL still elevated]:::action B -->|No| G[Initiate standard statin]:::action G --> H[Suboptimal response expected]:::outcome ``` ## Rationale for Correct Answer **High-Yield:** FH requires: 1. **Genetic confirmation** via testing (LDL receptor, APOB, PCSK9 mutations) to enable cascade screening of family members 2. **High-intensity statin therapy** (atorvastatin 80 mg or rosuvastatin 40 mg) as first-line, not standard-dose statin 3. **Early aggressive lipid-lowering** to reduce cardiovascular events by 50–70% compared to untreated FH **Clinical Pearl:** Patients with FH have LDL receptor defects; standard statins (which upregulate LDL receptors) are less effective than in polygenic hypercholesterolaemia. High-dose therapy compensates by maximally inhibiting HMG-CoA reductase and reducing cholesterol synthesis. ## Why High-Intensity Statin + Genetic Referral? - **Genetic testing** confirms FH diagnosis, enables family screening (autosomal dominant; ~50% of first-degree relatives affected), and guides cascade prevention - **High-intensity statin** is guideline-mandated for FH (European Atherosclerosis Society, ACC/AHA) because standard-dose statins undershoot LDL goals in these patients - **Ezetimibe and PCSK9 inhibitors** are added sequentially only if LDL goals are not met on statin monotherapy ## LDL Target in FH **Key Point:** LDL-C target in heterozygous FH is <100 mg/dL (ideally <70 mg/dL if established ASCVD). This patient's LDL of 180 mg/dL requires aggressive intervention. [cite:Harrison 21e Ch 397]