Cardiovascular

Familial hypercholesterolemia: diagnosis and aggressive management

Clinical Overview and When to Suspect Familial Hypercholesterolemia

— Heterozygous FH (HeFH): prevalence ~1 in 250 in the US — one of the most common monogenic disorders, yet <10% are diagnosed.

— Homozygous FH (HoFH): ~1 in 300,000; LDL often >400 mg/dL, MI/aortic stenosis in childhood/adolescence.

— Adult LDL-C ≥190 mg/dL (untreated) — automatic high-risk per ACC/AHA, treat as if FH until proven otherwise.

— Child/adolescent LDL-C ≥160 mg/dL (or ≥130 with FH family history).

— Premature ASCVD: men <55, women <65, especially with elevated LDL.

— First-degree relative with known FH or premature ASCVD.

— Tendon xanthomas, corneal arcus before age 45, or tuberous xanthomas at any age.

Familial hypercholesterolemia (FH) is an autosomal dominant disorder of LDL receptor pathway function causing lifelong elevation of LDL-C and dramatically accelerated atherosclerotic cardiovascular disease (ASCVD).

Pathophysiology: mutations in LDLR (~85%), APOB (~5–10%), PCSK9 gain-of-function (~1%), rarely LDLRAP1 (autosomal recessive).

Untreated HeFH risk of CAD by age 60: ~50% in men, ~30% in women. Treated early, near-normal life expectancy.

When to suspect FH in family medicine practice:

Universal pediatric lipid screening (NHLBI, AAP): one-time non-fasting non-HDL or fasting lipid panel between ages 9–11, repeat ages 17–21. This is a Step 3 preventive medicine staple — it exists primarily to catch FH before plaque accrues.

Board pearl: Any adult with LDL ≥190 mg/dL gets high-intensity statin regardless of 10-year ASCVD risk score — pooled cohort equations underestimate risk in FH because they assume average lifetime exposure, not lifelong exposure since birth.

Step 3 management: When you identify an index case, cascade screen all first-degree relatives (parents, siblings, children) with a lipid panel — single most cost-effective genetic screening strategy in medicine.

Presentation Patterns and Key History

— Asymptomatic young adult with strikingly elevated LDL on routine screening (e.g., 28-year-old non-obese man, LDL 245, TG normal).

— Premature MI in 30s–40s with "out of proportion" lipid panel and family history of early cardiac death.

— Child flagged on universal screening with LDL 200+, parent with known hypercholesterolemia.

— Cascade-identified relative of a known FH proband.

— Three-generation pedigree: premature CAD (M<55, F<65), sudden cardiac death, stroke, CABG/PCI, known hyperlipidemia, xanthomas.

— Personal ASCVD: angina, claudication, TIA symptoms, exertional dyspnea.

— Secondary causes to exclude before labeling as FH: untreated hypothyroidism, nephrotic syndrome, cholestatic liver disease, anorexia, medications (thiazides, atypical antipsychotics, cyclosporine, glucocorticoids, retinoids, protease inhibitors).

— Diet/lifestyle (helps but cannot explain LDL ≥190 in a lean patient).

— Pregnancy history in women (lipids rise physiologically — interpret with caution).

The deceptive feature of FH is silence — patients are usually asymptomatic until a premature coronary event. Detection is almost entirely lab- and family-history-driven, making it a quintessential preventive medicine topic.

Presentation archetypes on Step 3:

Targeted history must cover:

Key distinction: Polygenic hypercholesterolemia vs FH — polygenic patients usually have LDL 160–220 with weaker family history and no xanthomas; FH typically shows LDL ≥190 plus first-degree relative with premature ASCVD or matching lipid phenotype. Genetic testing resolves ambiguous cases but is not required for treatment.

Board pearl: A normal TSH and urine protein dipstick effectively rule out the two most common secondary mimics in a young adult with isolated LDL elevation — order them once before committing to a lifelong FH label.

Step 3 management: Document the pedigree in the chart and flag the EHR — this drives cascade testing and is a measurable quality metric in value-based primary care.

Physical Exam Findings and Vascular Assessment

— Tendon xanthomas — firm, painless nodules in Achilles tendon and extensor tendons of the hand (MCPs). Achilles thickening >9 mm on palpation/ultrasound is highly specific.

— Tuberous xanthomas — yellowish nodules on elbows, knees, buttocks.

— Xanthelasma — yellow plaques on eyelids; less specific (can occur with normal lipids), but in a young patient is suspicious.

— Corneal arcus before age 45 — white/grey ring at corneal limbus; in young adults this is highly suggestive of FH (in elderly it is normal aging — "arcus senilis").

— Cutaneous planar xanthomas in interdigital webs (especially between thumb and index finger) — virtually pathognomonic for HoFH.

— Supravalvular aortic stenosis from cholesterol deposition — listen for a harsh systolic murmur radiating to the carotids in a child.

— Carotid bruits, diminished pedal pulses, abdominal aortic palpation.

— Ankle-brachial index if claudication or absent pulses.

— Cardiac exam for AS murmur (aortic valve cholesterol deposition).

— Funduscopy: lipemia retinalis is rare (TG-driven), not classic FH.

Most FH patients have a normal exam, especially under age 30. Classic stigmata develop with cumulative LDL exposure and are more prevalent in HoFH or longstanding untreated HeFH.

Pathognomonic / highly suggestive findings:

HoFH-specific findings (pediatric/adolescent):

Vascular assessment in adult FH:

Key distinction: Eruptive xanthomas (small yellow papules on buttocks/extensor surfaces) reflect severe hypertriglyceridemia (TG >1000), not FH — different disease, different urgency (pancreatitis risk).

Board pearl: Tendon xanthomas are the single most specific physical finding for FH — their presence essentially confirms the diagnosis clinically using Dutch Lipid Clinic Network criteria, even before genetic testing.

Step 3 management: Palpate Achilles tendons and inspect extensor MCPs in any patient with LDL ≥190 — a 30-second exam maneuver with high diagnostic yield.

Diagnostic Workup — Initial Labs and Cardiovascular Assessment

— Repeat fasting lipid panel (or non-fasting if TG <400) to confirm LDL elevation; calculate LDL by Friedewald (invalid if TG >400 — use direct LDL or Martin/Hopkins equation).

— Document two separate elevated readings before labeling as FH.

— TSH — hypothyroidism elevates LDL.

— Urinalysis + spot urine protein/creatinine — nephrotic syndrome.

— Comprehensive metabolic panel — LFTs, creatinine, glucose/HbA1c.

— Fasting glucose or A1c — diabetes worsens dyslipidemia.

— Medication review (see chunk 2).

— Consider pregnancy test in women of reproductive age.

— Points for family history of premature CAD or high LDL, personal history of premature CAD, physical findings (tendon xanthomas, arcus <45), LDL level, and DNA analysis.

— >8 = definite, 6–8 probable, 3–5 possible FH.

— Simon Broome and MEDPED are alternatives.

— 12-lead ECG at baseline in adults.

— Lp(a) — measure once in every FH patient; elevation (>50 mg/dL or >125 nmol/L) markedly amplifies risk and may shift treatment intensity.

— hs-CRP optional adjunct.

— Coronary artery calcium (CAC) can refine risk in select adults ≥40 but is not required to treat — CAC = 0 does not lower the bar for statin in FH because young calcified plaque is uncommon.

— Carotid intima-media thickness — used in research, not routine.

Confirm the lipid abnormality:

Exclude secondary hyperlipidemia (mandatory before diagnosis):

Apply clinical diagnostic criteria — most commonly Dutch Lipid Clinic Network (DLCN) score:

Baseline cardiovascular risk assessment:

CCS pearl: Order the lipid panel, TSH, UA, CMP, and Lp(a) at the same visit — bundling avoids repeat phlebotomy and accelerates time-to-treatment, a Step 3 efficiency principle.

Board pearl: Lp(a) is genetically determined and measured once per lifetime — it does not require fasting and is not lowered by statins (may rise slightly). It identifies the FH patient who needs the most aggressive LDL lowering.

Diagnostic Workup — Genetic Testing and Advanced Imaging

— Panel covers LDLR, APOB, PCSK9, LDLRAP1.

— Indications: ambiguous clinical picture, suspected HoFH, facilitation of cascade screening in relatives, patient/family preference, insurance authorization for PCSK9 inhibitors in some plans.

— A negative panel does not exclude FH — ~20–40% of clinically definite FH have no identifiable mutation (polygenic contribution).

— A positive result confirms diagnosis and powerfully motivates relatives.

— If proband has known mutation → relatives get targeted genetic testing plus lipid panel (highly sensitive/specific).

— If no mutation identified → relatives screened by lipid panel alone using age-/sex-specific LDL cutoffs.

— Children of an FH parent should be screened starting at age 2 if HoFH suspected, otherwise by ages 9–11.

— CAC scoring in asymptomatic adults ≥30–40 to gauge subclinical plaque burden and reinforce adherence.

— Coronary CT angiography if atypical symptoms or borderline stress test.

— Stress testing for any chest pain, dyspnea on exertion, or before strenuous exercise initiation in older FH patients.

— Echocardiogram in HoFH (screen for supravalvular and valvular aortic stenosis) — repeat periodically.

Genetic testing in FH — useful but not required to make the diagnosis or initiate treatment.

Cascade screening of first-degree relatives:

Advanced cardiovascular imaging — when to consider:

Key distinction: Clinical diagnosis (DLCN ≥6 or LDL ≥190 with consistent family history) is sufficient to initiate high-intensity statin — do not delay treatment awaiting genetic results.

Board pearl: Genetic testing is best framed to patients as a tool for family screening, not personal treatment decisions — a frequent counseling vignette on Step 3 communication skills questions.

Step 3 management: Refer to a lipid specialist or preventive cardiology if HoFH suspected (LDL >400, early xanthomas, family history of childhood MI) or LDL targets unmet on maximal oral therapy — these patients need PCSK9 inhibitors, lipoprotein apheresis, or evinacumab.

Risk Stratification and Treatment Targets

— Adult HeFH without ASCVD: ≥50% LDL reduction from baseline, target LDL <100 mg/dL (NLA <100; ESC <70).

— Adult HeFH with established ASCVD or diabetes or Lp(a) elevation: ≥50% reduction and LDL <70 mg/dL (ESC: <55).

— HoFH: treat aggressively to lowest achievable LDL; targets <100 (no ASCVD) or <70 (with ASCVD), often requires combination therapy + apheresis.

— Children with HeFH: initiate statin at age 8–10 if LDL ≥190, or ≥160 with family history of premature CAD/additional risk factors; target ≥50% LDL reduction or LDL <130.

— Established ASCVD (MI, stroke, PAD, revascularization).

— Lp(a) ≥50 mg/dL.

— Diabetes mellitus.

— Current smoking.

— Hypertension.

— CKD stage ≥3.

— Family history of very premature ASCVD (<45).

— HoFH or biallelic mutations.

— Emphasize lifetime LDL burden ("cholesterol-years") — starting therapy at 25 vs 45 prevents far more events than the same therapy started two decades later.

— Use shared decision-making about statin initiation in children and adolescents.

All FH patients are categorically high or very high ASCVD risk — the pooled cohort equation underestimates risk and should not be used to decide whether to treat.

LDL-C goals (composite of ACC/AHA 2018, NLA, and European guidance commonly tested):

Risk amplifiers that mandate more aggressive targets:

Risk communication framing for adherence:

Step 3 management: Reassess LDL 4–12 weeks after initiating or titrating therapy, then every 3–12 months. Document percent reduction from baseline, not just absolute LDL — this is the metric the guidelines and exam care about.

Board pearl: In an FH stem, even if LDL falls to 85 on therapy, if the percent reduction is <50%, treatment is still inadequate — intensify rather than declare success.

Pharmacotherapy — First-Line Statin Regimen

— Atorvastatin 40–80 mg daily or rosuvastatin 20–40 mg daily — expected LDL reduction ~50% or more.

— Start at the high-intensity dose; do not titrate up from low-intensity in known FH.

— Take rosuvastatin or atorvastatin any time of day; short-acting statins (simvastatin, pravastatin) in the evening.

— ALT (hepatic baseline) — routine periodic monitoring not required unless symptoms.

— CK only if symptomatic or high-risk for myopathy.

— A1c or fasting glucose — statins slightly raise diabetes risk; benefit outweighs.

— Lipid panel at 4–12 weeks, then 3–12 months.

— Counsel on muscle symptoms — true statin-associated muscle symptoms (SAMS) occur in <5% in blinded trials; nocebo effect dominates open-label complaints.

— If muscle symptoms: hold statin, recheck CK, rule out hypothyroidism/vitamin D deficiency/drug interactions; rechallenge with same or alternate statin, often at lower dose or alternate-day rosuvastatin.

— Add ezetimibe 10 mg daily — additional ~18–25% LDL reduction; IMPROVE-IT showed event reduction.

— Add bempedoic acid 180 mg daily — ~17–18% additional LDL drop; CLEAR Outcomes showed CV benefit, particularly for statin-intolerant patients (no muscle symptoms — acts upstream of HMG-CoA reductase).

— Add PCSK9 monoclonal antibody (evolocumab, alirolocumab) — additional ~50–60% LDL reduction on top of statin/ezetimibe.

— Inclisiran (siRNA targeting PCSK9) — subcutaneous q6 months after loading; convenient for adherence.

— Simvastatin + amiodarone/amlodipine/diltiazem → dose limits.

— Statins + cyclosporine, gemfibrozil → myopathy risk (use fenofibrate instead).

High-intensity statin is first-line for every adult FH patient, irrespective of baseline LDL or ASCVD status.

Pre-statin baseline labs:

Monitoring on therapy:

Combination therapy when statin alone insufficient (very common in FH):

Drug interactions to flag:

Board pearl: Ezetimibe is the preferred second agent after high-intensity statin in FH because of cost, oral route, and outcomes data — add it before escalating to a PCSK9 inhibitor.

Advanced Pharmacotherapy and Lipoprotein Apheresis

— Evolocumab 140 mg SC q2 weeks or 420 mg monthly; alirocumab 75–150 mg SC q2 weeks.

— FOURIER and ODYSSEY OUTCOMES: 15–20% reduction in major CV events.

— Indicated in FH when LDL remains above target on maximally tolerated statin + ezetimibe, or in established ASCVD with LDL ≥70.

— Side effects: mild injection-site reactions; well tolerated; no signal for cognitive or hepatic harm.

— Dosing: SC at day 0, day 90, then every 6 months — adherence-friendly.

— ~50% LDL reduction; cardiovascular outcomes trial pending but FDA-approved for HeFH and ASCVD adjunct.

— Useful in statin-intolerant patients.

— Mild uric acid elevation, gout risk; mild tendon rupture risk reported.

— Specifically for HoFH; lowers LDL ~50% via LDLR-independent mechanism — works even in receptor-negative patients.

— Indicated for HoFH and severe HeFH with progressive ASCVD despite maximal therapy.

— Every 1–2 weeks; acutely lowers LDL by 60–75%.

— Often combined with PCSK9 inhibitor or evinacumab.

— Aspirin 81 mg for secondary prevention.

— Icosapent ethyl 2 g BID if TG 150–499 on statin with ASCVD or diabetes (REDUCE-IT).

— Optimize BP, diabetes, smoking cessation.

PCSK9 inhibitors — backbone of refractory FH care.

Inclisiran — small interfering RNA silencing hepatic PCSK9 mRNA.

Bempedoic acid — ATP-citrate lyase inhibitor, activated only in liver (skeletal muscle spared).

Evinacumab — anti-ANGPTL3 monoclonal IV infusion.

Lomitapide (MTP inhibitor) and mipomersen (apoB antisense, withdrawn US) — niche HoFH agents, hepatic steatosis limits use.

Lipoprotein apheresis:

Adjunctive therapy in established ASCVD:

Step 3 management: Insurance authorization for PCSK9 inhibitors typically requires documented 3-month trial of maximally tolerated statin + ezetimibe with persistent LDL above target — anticipate prior auth and document attempts meticulously.

Board pearl: Evinacumab is the only LDL-lowering agent that works in LDLR-null HoFH — a high-yield trivia point for HoFH vignettes.

Special Populations — Elderly, Renal, and Hepatic Considerations

— Most have lived with elevated LDL for decades; continue or initiate statin if functional, especially with established ASCVD.

— For primary prevention >75, shared decision-making — but a known FH diagnosis tips toward treatment because lifetime risk is high.

— Start at moderate intensity if frail and titrate; watch drug interactions (polypharmacy).

— Atorvastatin and pravastatin preferred — no renal dose adjustment for atorvastatin.

— CKD itself is an ASCVD risk amplifier — treat FH more aggressively.

— Rosuvastatin: max 10 mg/day if CrCl <30 (not on dialysis).

— Atorvastatin: no renal dose adjustment — often preferred in advanced CKD.

— Ezetimibe: no adjustment.

— PCSK9 inhibitors: no renal adjustment, safe in dialysis.

— Avoid statin initiation de novo in dialysis patients without prior CV event (SHARP, AURORA, 4D — minimal benefit in this specific group), but continue if already on therapy.

— Statins contraindicated in active liver disease or unexplained persistent ALT/AST >3× ULN.

— Compensated NAFLD/NASH is not a contraindication — statins are safe and may benefit.

— Routine LFT monitoring not required; check if symptomatic.

— Lomitapide is hepatotoxic — REMS program, frequent LFTs.

— Amiodarone, diltiazem, verapamil, macrolides (clarithromycin, erythromycin), azole antifungals, HIV protease inhibitors — CYP3A4 interactions elevate simvastatin/atorvastatin/lovastatin levels.

— Rosuvastatin and pravastatin less affected by CYP3A4.

Elderly FH patients (≥75):

Chronic kidney disease:

Hepatic impairment:

Drug-drug interaction hotspots in elderly:

Key distinction: Dialysis patient with established ASCVD on a statin → continue; dialysis patient never on a statin without ASCVD → generally don't start de novo, but FH patients are an exception — lifetime LDL burden justifies treatment.

Board pearl: Switch a dialysis FH patient from rosuvastatin 40 mg to atorvastatin 40–80 mg or rosuvastatin 10 mg max — a frequent CCS-style adjustment vignette.

Special Populations — Pregnancy, Lactation, and Pediatrics

— Statins were formerly Pregnancy Category X; FDA in 2021 removed the broad contraindication — risk is now considered low but they remain generally not recommended during pregnancy or while attempting conception.

— Discontinue statins, ezetimibe, PCSK9 inhibitors, and bempedoic acid 1–3 months before conception and throughout pregnancy/lactation.

— Exception: women with HoFH or severe ASCVD — individualized continuation may be justified; coordinate with MFM and lipid specialist.

— Bile acid sequestrants (cholestyramine, colesevelam) are the only oral lipid agents considered safe in pregnancy (not systemically absorbed); modest LDL reduction (~15–20%).

— Lipoprotein apheresis is safe in pregnancy and used in severe FH.

— Counsel on contraception in reproductive-age women on lipid therapy.

— Statins generally avoided; pravastatin has the least lipophilicity if absolutely needed.

— Bile acid sequestrants and apheresis compatible.

— Universal screening at ages 9–11 and again 17–21 (NHLBI/AAP).

— Targeted/cascade screening as young as age 2 if HoFH suspected or strong family history.

— Initiate statin at age 8–10 in HeFH if:

— LDL ≥190, OR

— LDL ≥160 with FH family history or ≥2 risk factors, OR

— LDL ≥130 with diabetes.

— Pravastatin, atorvastatin, rosuvastatin, simvastatin FDA-approved in pediatrics (age cutoffs vary).

— Ezetimibe approved ≥10 years.

— Evolocumab approved ≥10 years for HeFH and HoFH.

— Goal: ≥50% LDL reduction or LDL <130.

— Monitor growth, puberty (no adverse effects shown in long-term cohorts).

Pregnancy:

Lactation:

Pediatric FH management:

Step 3 management: A 9-year-old with LDL 240 and a father who had MI at 38 → lifestyle counseling + initiate statin — do not defer to adulthood; cumulative LDL exposure is the modifiable variable.

Board pearl: Cholestyramine and colesevelam are the go-to lipid agents for the pregnant FH patient — memorize this pair.

Complications and Adverse Outcomes

— Premature coronary artery disease — MI in 30s–40s for untreated HeFH, often earlier in HoFH.

— Acute coronary syndromes, sudden cardiac death.

— Stroke and TIA (less common than CAD but elevated).

— Peripheral arterial disease, claudication, critical limb ischemia.

— Aortic stenosis — cholesterol deposition on aortic valve, particularly in HoFH; supravalvular AS in children.

— Carotid stenosis.

— MI as early as age 5–10 in untreated HoFH.

— Aortic root and supravalvular cholesterol deposition causing outflow obstruction.

— Coronary ostial stenosis from aortic deposition.

— Statin-associated muscle symptoms (SAMS) — myalgia ~5% in blinded trials; severe myopathy with CK >10× ULN rare; rhabdomyolysis very rare (~1 in 10,000 patient-years).

— Statin-induced diabetes — modest absolute risk increase, outweighed by CV benefit.

— Hepatotoxicity — clinically significant elevation <1%, reversible.

— Immune-mediated necrotizing myopathy (anti-HMGCR antibodies) — rare, persists after statin discontinuation, requires immunosuppression.

— Bempedoic acid: gout flares, mild tendon rupture risk.

— PCSK9 inhibitors: injection site reactions; rare hypersensitivity.

— Lomitapide/mipomersen: hepatic steatosis, GI side effects.

— Anxiety from "genetic" framing — counsel on excellent prognosis with treatment.

— Adherence challenges in asymptomatic youth — cumulative non-adherence drives event risk.

Cardiovascular complications — the dominant morbidity of FH:

Pediatric/HoFH-specific:

Treatment-related complications:

Psychosocial:

Key distinction: Routine CK and LFT monitoring on statins is not recommended in asymptomatic patients — check only for clinical indication (muscle symptoms, jaundice). This is a frequent over-testing trap on Step 3.

Board pearl: New muscle weakness persisting weeks after statin discontinuation with markedly elevated CK should trigger workup for autoimmune necrotizing myopathy — anti-HMGCR antibody testing and rheumatology referral.

When to Escalate Care — Specialist Referral and Inpatient Triage

— Suspected HoFH (LDL >400, planar xanthomas, childhood MI, both parents with FH).

— LDL not at goal despite maximally tolerated statin + ezetimibe + PCSK9 inhibitor.

— Recurrent statin intolerance after multiple rechallenges.

— Need for lipoprotein apheresis, evinacumab, lomitapide.

— Genetic counseling for complex pedigrees.

— Pediatric FH (refer to pediatric lipid clinic by adolescence).

— Pregnancy with known FH.

— Index case identified — facilitate cascade testing.

— Patient considering pregnancy.

— Discordance between genotype and phenotype.

— Symptomatic ASCVD — chest pain, claudication, TIA.

— Abnormal stress test or CAC very high for age.

— Suspected aortic valve involvement (murmur, echo findings).

— Acute coronary syndrome symptoms → ED, troponin, ECG, ASA, anticoagulation.

— Acute stroke symptoms → activate stroke pathway.

— Rhabdomyolysis — severe muscle pain with CK >10× ULN, dark urine, AKI → admit for IV hydration, hold statin.

— Severe hypertriglyceridemia–associated pancreatitis (different syndrome but co-managed).

— Cardiology, lipidology, genetics, pediatrics, MFM, dietitian, pharmacist.

— In HoFH, plan apheresis access (often tunneled or AV fistula).

Refer to lipid specialist / preventive cardiology when:

Refer for genetic counseling when:

Refer to cardiology when:

Hospitalization triggers — Step 3 outpatient-to-inpatient transitions:

Multidisciplinary considerations:

CCS pearl: A 42-year-old FH patient presenting with new exertional chest pain → EKG, troponin, aspirin, admit telemetry, cardiology consult — do not minimize symptoms in this population; pretest probability is extraordinarily high.

Step 3 management: Establish a shared care plan between primary care (longitudinal lipid management, cascade screening, adherence) and lipidology/cardiology (advanced therapy, procedures) — explicit role delineation prevents care fragmentation, a tested patient-safety competency.

Key Differentials — Other Causes of Severe Hypercholesterolemia

— LDL typically 160–220; weaker family history.

— No tendon xanthomas.

— Cumulative effect of many small-effect SNPs.

— Treatment similar but targets less stringent; ASCVD risk assessed by pooled cohort equation.

— Most common familial dyslipidemia (~1–2% population).

— Both LDL and triglycerides elevated, often with low HDL.

— Variable phenotype within a family — some members elevated LDL, others elevated TG.

— Associated with metabolic syndrome, insulin resistance, central adiposity.

— No tendon xanthomas.

— Premature ASCVD risk elevated but less than FH.

— Apo E2/E2 homozygosity plus a second hit (diabetes, hypothyroidism, obesity).

— Both cholesterol and TG elevated (~300–600 each), roughly 1:1 ratio.

— Palmar xanthomas (xanthoma striatum palmare) — pathognomonic yellow-orange creases in palms.

— Tuberoeruptive xanthomas on elbows/knees.

— Diagnose via lipoprotein electrophoresis (broad beta band) or apoE genotyping.

— Treats well with statin + fibrate.

— Rare autosomal recessive (ABCG5/ABCG8).

— Mimics HoFH with xanthomas and early ASCVD.

— Hemolytic anemia, stomatocytes, thrombocytopenia.

— Plant sterols elevated on serum testing — diagnostic.

— Treatment: ezetimibe (highly effective), low-plant-sterol diet — statins less effective.

— CYP27A1 mutation, cholestanol accumulation.

— Tendon xanthomas, juvenile cataracts, progressive neurologic decline, chronic diarrhea.

— LDL often normal — cholestanol elevated.

— Treat with chenodeoxycholic acid.

Polygenic hypercholesterolemia:

Familial combined hyperlipidemia (FCHL):

Familial dysbetalipoproteinemia (Type III, broad beta disease):

Sitosterolemia:

Cerebrotendinous xanthomatosis (CTX):

Key distinction: Tendon xanthomas with normal LDL → think CTX or sitosterolemia, not FH.

Board pearl: Palmar xanthomas = dysbetalipoproteinemia; Achilles xanthomas = FH; eruptive xanthomas = severe hypertriglyceridemia — memorize the xanthoma map.

Key Differentials — Secondary Hyperlipidemia

— Most common reversible cause of elevated LDL.

— Mechanism: reduced LDL receptor expression.

— Check TSH in every new hypercholesterolemia workup.

— Treat hypothyroidism first; recheck lipids in 6–8 weeks before committing to lifelong statin.

— Proteinuria >3.5 g/day, hypoalbuminemia, edema.

— Hepatic compensatory lipoprotein overproduction.

— Spot urine protein/creatinine or 24-hour urine; serum albumin.

— Treat underlying glomerular disease; statin often added.

— Mixed dyslipidemia with elevated TG, lower HDL.

— Worsens with declining GFR.

— Markedly elevated cholesterol (lipoprotein X).

— Xanthomas/xanthelasma common.

— ALP elevated; AMA positive in PBC.

— Thiazides, beta-blockers (modest TG elevation).

— Atypical antipsychotics (olanzapine, clozapine).

— Glucocorticoids.

— Cyclosporine, tacrolimus.

— Retinoids (isotretinoin).

— HIV protease inhibitors.

— Estrogen (oral, not transdermal — raises TG).

— Anabolic steroids (lowers HDL).

— Atherogenic dyslipidemia: high TG, low HDL, small dense LDL — LDL itself may be normal.

— Treat as ASCVD risk equivalent.

— Paradoxically elevated cholesterol from impaired bile acid synthesis.

— Physiologic LDL and TG rise — interpret carefully.

— Raises TG, mildly raises HDL.

Hypothyroidism:

Nephrotic syndrome:

Chronic kidney disease (especially advanced):

Cholestatic liver disease (PBC, biliary obstruction):

Medications — review at every visit:

Diabetes mellitus:

Anorexia nervosa:

Pregnancy:

Excess alcohol:

Key distinction: Before diagnosing FH, ensure TSH is normal, no proteinuria, no relevant offending medication — secondary causes are common, often missed, and reversible.

Step 3 management: A patient with LDL 250 and TSH 18 → treat hypothyroidism with levothyroxine, recheck lipids at 8 weeks. If LDL remains ≥190, then pursue FH workup and statin therapy.

Secondary Prevention and Long-Term Treatment Plan

— Smoking cessation — counsel at every visit; pharmacotherapy (varenicline, bupropion, NRT).

— Blood pressure target <130/80 (ACC/AHA) in high-risk patients.

— Diabetes control — A1c <7% generally, individualized.

— Weight — target BMI <25; refer for intensive behavioral counseling if BMI ≥30.

— Physical activity — 150 min/week moderate aerobic + 2 sessions resistance.

— Diet — Mediterranean or DASH; saturated fat <6% of calories; emphasize whole grains, legumes, nuts, fish.

— High-intensity statin + ezetimibe baseline.

— Add PCSK9 inhibitor if LDL above target.

— Consider inclisiran for adherence-challenged patients.

— Add bempedoic acid for statin intolerance or additional reduction.

— Aspirin 81 mg for secondary prevention (post-MI/stroke/PAD); not routine in primary prevention even in FH unless very high risk and low bleeding risk — individualize.

— Beta-blocker, ACEi/ARB post-MI per guidelines.

— Once-daily dosing; combination pills.

— 90-day prescriptions, mail order.

— Pharmacist medication-therapy management.

— Behavioral nudges, text reminders.

— Address nocebo effect with patient education.

Comprehensive ASCVD risk-factor management is as important as LDL lowering:

Long-term pharmacologic stack for FH:

Adherence strategies:

Vaccinations — annual influenza, pneumococcal, COVID-19 boosters per CDC (reduces CV events post-influenza).

Cardiac rehabilitation post-ACS or revascularization — Medicare-covered, underutilized.

Step 3 management: At each annual visit, review (1) LDL goal attainment, (2) BP, (3) glucose, (4) smoking, (5) adherence, (6) cascade screening status of family, (7) any new ASCVD symptoms — a structured FH visit template improves outcomes and is a value-based-care quality metric.

Board pearl: In FH, aspirin is not automatic primary prevention — apply standard ACC/AHA logic (age 40–70, high ASCVD risk, low bleeding risk, shared decision-making). Many FH stems test this nuance.

Follow-Up, Monitoring, and Counseling Cadence

— Baseline before initiating therapy.

— 4–12 weeks after starting or changing therapy — assess response and adherence.

— Once at goal: every 3–12 months depending on stability.

— Earlier follow-up if adherence concerns, intolerance, or comorbid changes.

— ALT at baseline; routine repeat unnecessary unless symptomatic.

— CK only if muscle symptoms; not routine.

— A1c or fasting glucose annually.

— Lp(a) — once per lifetime, no need to repeat.

— Blood pressure every visit; weight every visit.

— ECG baseline and as clinically indicated.

— CAC baseline if used for risk communication; repeat every 5 years not generally indicated once on therapy.

— Carotid duplex if symptomatic or bruit.

— Echocardiogram every 1–5 years in HoFH for aortic valve surveillance.

— Document each first-degree relative screened.

— Re-engage annually until all family members are evaluated.

— Pediatric relatives: re-screen at ages 9–11 and 17–21 if initial panel normal.

— Diet — Mediterranean pattern; plant sterols/stanols 2 g/day reduce LDL ~10%; soluble fiber.

— Exercise — structured plan, document.

— Tobacco/alcohol assessment.

— Mental health screening (PHQ-2/9) — chronic disease + family burden.

Lipid monitoring cadence:

Other monitoring:

Imaging cadence:

Family/cascade screening monitoring:

Lifestyle counseling at each visit:

Cardiac rehab post-event, 36 sessions over 12 weeks.

Step 3 management: At every visit, ask explicitly: "Are you taking your statin every day?" Use a non-judgmental motivational interviewing frame ("Many patients miss doses — how often does that happen for you?"). Adherence is the single biggest modifiable lever in long-term FH outcomes.

Board pearl: Routine LFT and CK monitoring on stable statin therapy is not recommended — order only for symptoms. Choosing not to check labs can be the correct Step 3 answer.

Ethical, Legal, and Patient Safety Considerations

— Pre-test counseling: discuss implications for patient, family, and reproductive choices.

— Post-test: positive results require disclosure planning for relatives.

— GINA (Genetic Information Nondiscrimination Act, 2008) prohibits health insurance and employment discrimination based on genetic information, but does not cover life, disability, or long-term care insurance — counsel patients before testing.

— Document informed consent for genetic testing.

— Physicians cannot directly contact at-risk relatives without consent (HIPAA).

— Counsel and encourage the patient to inform first-degree relatives; offer letters/scripts they can share.

— Most jurisdictions consider notifying relatives a moral but not legal duty.

— Children ≥7 should provide assent; parents provide consent.

— Discuss medication initiation as shared decision; address adolescent autonomy and adherence.

— Document discussion of teratogenicity concerns and contraception in reproductive-age women on lipid therapy.

— Preconception planning visit for known FH women.

— Post-MI discharge: ensure high-intensity statin is on the discharge med list — a tested quality measure (statin-at-discharge after ACS). Medication reconciliation at every transition.

— Hospital-to-home handoff: schedule lipid recheck 4–6 weeks post-discharge with PCP; communicate to the patient and document in the after-visit summary.

— Avoid inappropriate statin discontinuation at transitions of care (common safety event when admitting team holds statin and never restarts).

— Document prior failed/maximally tolerated therapy for PCSK9 inhibitor authorization.

— Connect uninsured/underinsured patients with manufacturer assistance programs.

Genetic testing — informed consent and counseling:

Duty to warn relatives — an ethical tension:

Pediatric FH and assent:

Reproductive counseling:

Patient safety / transition of care issues:

Insurance and access:

Step 3 management: A 35-year-old genetically confirmed FH patient asks if he must tell his sister. Counsel that you cannot disclose without consent, but strongly encourage him, provide written materials, and document the discussion — a classic Step 3 ethics vignette.

Board pearl: GINA protects health/employment, not life/disability insurance — high-yield testable nuance.

High-Yield Associations and Rapid-Fire Clinical Facts

Inheritance: Autosomal dominant; HeFH ~1:250, HoFH ~1:300,000.

Genes: LDLR (85%), APOB (5–10%), PCSK9 gain-of-function (1%), LDLRAP1 (recessive).

Untreated HeFH life expectancy: reduced ~20 years; treated near-normal.

HoFH untreated: MI in first/second decade; survival without therapy often <30 years.

Dutch Lipid Clinic Network ≥8 = definite FH.

LDL ≥190 mg/dL adult or ≥160 child with first-degree relative with premature ASCVD = clinical FH.

Tendon xanthomas — most specific physical sign.

Corneal arcus before age 45 — suspicious.

Palmar xanthomas — dysbetalipoproteinemia (Apo E2/E2).

Eruptive xanthomas — TG >1000, pancreatitis risk.

Universal pediatric lipid screening: ages 9–11 and 17–21.

Initiate statin in pediatric FH at age 8–10.

Cascade screen all first-degree relatives of any FH index case.

Goals: ≥50% LDL reduction; LDL <100 (no ASCVD), <70 with ASCVD/diabetes/elevated Lp(a).

Lp(a) measured once per lifetime; amplifies risk; not lowered by statins.

First-line: high-intensity statin (atorva 40–80, rosuva 20–40).

Second-line: ezetimibe.

Third-line: PCSK9 inhibitor (evolocumab, alirocumab) or inclisiran.

Statin-intolerant alternative: bempedoic acid.

HoFH special: evinacumab (anti-ANGPTL3), lomitapide, apheresis.

Pregnancy-safe agents: bile acid sequestrants (cholestyramine, colesevelam), apheresis.

Dialysis: atorvastatin preferred; don't start de novo in pure CKD, but FH is an exception.

GINA: protects health/employment, not life/disability/LTC insurance.

Aortic stenosis in HoFH from cholesterol valve deposition.

Supravalvular AS murmur in HoFH child.

Interdigital web xanthomas (between thumb and index finger) = HoFH pathognomonic.

Board pearl: Achilles tendon thickening >9 mm on ultrasound or palpation in a young hypercholesterolemic = strong evidence for FH; one of the highest-yield physical findings on Step 3.

Key distinction: FH ≠ polygenic hypercholesterolemia ≠ FCHL ≠ dysbetalipoproteinemia — each has distinctive lipid pattern, family history, and exam findings.

Board Question Stem Patterns

— 28-year-old man, lean, BMI 23, BP normal, LDL 245, TG 90, HDL 50, father had MI at 42.

— Trap: calculating ASCVD risk score (will be low).

— Answer: initiate high-intensity statin based on LDL ≥190; do not use risk calculator.

— Bonus: order TSH, UA, Lp(a), cascade screen relatives.

— 10-year-old, LDL 215 on universal screening, mother with hypercholesterolemia and bypass at 45.

— Answer: initiate statin therapy (atorvastatin or pravastatin) with lifestyle counseling. Defer to adolescence is wrong.

— 30-year-old FH patient on rosuvastatin, planning conception.

— Answer: discontinue statin 1–3 months before conception, switch to colesevelam if treatment needed; consider apheresis if severe.

— 8-year-old with planar xanthomas in finger webs, LDL 620, harsh systolic murmur radiating to carotids.

— Answer: suspect HoFH with supravalvular aortic stenosis; refer lipid specialist for evinacumab/apheresis; echo.

— Patient on atorvastatin developed myalgia, held statin, symptoms resolved; rosuvastatin retried with same issue.

— Answer: trial alternate-day rosuvastatin or bempedoic acid; add ezetimibe; if LDL still above goal, PCSK9 inhibitor.

— 45-year-old with LDL 245, fatigue, constipation, weight gain, TSH 22.

— Answer: treat hypothyroidism first, recheck lipids in 6–8 weeks before diagnosing FH.

— FH patient declines to inform siblings.

— Answer: counsel, encourage, provide written materials, document — do not contact relatives directly.

— Patient discharged after MI without statin on med list.

— Answer: initiate high-intensity statin before discharge.

Stem 1 — Young adult with isolated high LDL:

Stem 2 — Pediatric vignette:

Stem 3 — Pregnancy:

Stem 4 — HoFH child:

Stem 5 — Statin intolerance:

Stem 6 — Apparent FH with confounder:

Stem 7 — Ethics:

Stem 8 — Post-MI quality measure:

Board pearl: When stem mentions LDL ≥190 OR tendon xanthomas OR childhood-onset hypercholesterolemia, default mental answer is high-intensity statin + cascade screen relatives — covers most FH stems.

Step 3 management: Always check for the "secondary cause" red herring (TSH, proteinuria, medication) before locking in the FH diagnosis on long stems.

One-Line Recap

Familial hypercholesterolemia is a common autosomal dominant disorder of LDL receptor pathway function that produces lifelong LDL elevation and dramatically premature ASCVD, demanding early recognition (LDL ≥190 in adults or ≥160 in children, often with tendon xanthomas and a family history of premature CAD), aggressive treatment with high-intensity statin plus ezetimibe and frequently a PCSK9 inhibitor to achieve ≥50% LDL reduction and target <70–100 mg/dL, and systematic cascade screening of every first-degree relative.

Diagnosis: Adult LDL ≥190 or child ≥160 with consistent family history; confirm with repeat panel after excluding hypothyroidism, nephrotic syndrome, and offending medications; apply Dutch Lipid Clinic Network criteria; genetic testing optional but useful for cascade screening; measure Lp(a) once.

Treatment: High-intensity atorvastatin or rosuvastatin first-line for everyone — bypass the pooled cohort equation; add ezetimibe early; escalate to PCSK9 inhibitor (evolocumab, alirocumab) or inclisiran if LDL above target; bempedoic acid for statin intolerance; evinacumab and apheresis reserved for HoFH or refractory severe HeFH.

Special populations: Initiate statin in pediatric FH at age 8–10; discontinue statins 1–3 months pre-conception and use colesevelam or apheresis during pregnancy; atorvastatin preferred in advanced CKD; treat elderly FH with shared decision-making but maintain therapy when established.

System-of-care priorities: Cascade screen all first-degree relatives — the single most cost-effective genetic screening intervention; never miss a post-ACS high-intensity statin at discharge; counsel under GINA limits regarding life/disability insurance; structure annual visits around LDL goal, BP, glucose, smoking, adherence, and family screening progress.

Board pearl: Default reflex for any FH stem — high-intensity statin + ezetimibe + cascade screen relatives, and never anchor on a normal ASCVD risk score when LDL ≥190.