Hyperlipidemia is an excess of cholesterol, triglycerides, or both in the blood, carried by lipoproteins. High LDL drives atherosclerosis; very high triglycerides cause pancreatitis. Step 1 tests how lipoproteins are built and cleared, the inherited disorders that break specific steps, their physical signs, and how each drug class fixes a step.
check_circleTreatment: statins first (β LDL, β events); add ezetimibe or PCSK9 inhibitors for LDL; fibrates or omega-3s for severe hypertriglyceridemia.
target What you'll be able to do Β· aligned to USMLE Step 1 Β· Biochemistry & Cardiovascular
BIOCHEMDescribe the structure, apolipoproteins, and metabolism of the major lipoproteins.
GENIdentify the defect, inheritance, and findings of major familial dyslipidemias.
PATHExplain how LDL contributes to atherosclerosis and how triglycerides cause pancreatitis.
PHARMSelect lipid-lowering drugs according to the lipid abnormality.
How hyperlipidemia is tested on Step 1
Expect a patient with xanthomas, early MI, or recurrent pancreatitis and a lipid panel, and a question about the defective protein, inheritance, or drug of choice.
workspace_premium Match the sign to the lipid
Tendon xanthomas and corneal arcus point to high LDL. Eruptive xanthomas, milky plasma, and pancreatitis point to very high triglycerides.
Lipoprotein metabolism
Lipoproteins are defined by their apolipoproteins, which act as structural proteins, enzyme cofactors, and receptor ligands.
Endogenous pathway. PCSK9 promotes LDL receptor degradation; blocking it leaves more receptors to clear LDL.
Apolipoprotein
Function
Lipoproteins
B-48
Assembly and secretion of chylomicrons
Chylomicrons
B-100
Binds LDL receptor
VLDL, IDL, LDL
C-II
Activates lipoprotein lipase
Chylomicrons, VLDL, HDL
E
Mediates remnant uptake by liver
Chylomicron remnants, VLDL, IDL, HDL
A-I
Activates LCAT (cholesterol esterification)
HDL
Lp(a) is LDL bound to apolipoprotein(a); high levels are an inherited cardiovascular risk factor.
TG often > 1,000 mg/dL, pancreatitis, eruptive xanthomas, hepatosplenomegaly; no β atherosclerosis
Familial hypercholesterolemia (type IIa)
LDL receptor (or apo B-100, PCSK9 gain)
Autosomal dominant
Heterozygotes LDL ~200β400 mg/dL, homozygotes > 500; tendon xanthomas, MI before age 20 in homozygotes
Dysbetalipoproteinemia (type III)
Apo E2 homozygosity
Autosomal recessive (needs second hit)
Palmar and tuberoeruptive xanthomas; premature vascular disease
Familial hypertriglyceridemia (type IV)
Hepatic VLDL overproduction
Autosomal dominant
High TG; pancreatitis risk when severe
Homozygous familial hypercholesterolemia responds poorly to statins because receptors are absent; PCSK9 inhibitors also need functioning receptors.
Atherosclerosis and treatment
LDL particles enter the arterial intima, become oxidized, and are taken up by macrophages, forming foam cells and fatty streaks that mature into plaques.
LDL vs triglycerides. Statins also lower triglycerides modestly and reduce cardiovascular events most.
Drug
Target step
Main lipid effect
Statins
HMG-CoA reductase β β LDL receptors
βββ LDL
Ezetimibe
NPC1L1 intestinal cholesterol absorption
β LDL
PCSK9 inhibitors
Prevent LDL receptor degradation
βββ LDL
Fibrates
PPAR-Ξ± β β lipoprotein lipase
βββ TG
Omega-3 fatty acids
β Hepatic VLDL production
β TG
Bile acid sequestrants
Bind bile acids β liver uses cholesterol
β LDL (β TG)
See the statin guide for intensity tiers, myopathy, and interactions.
Clinical application
Physical signs plus family history often make the diagnosis.
functions Worked example β the knuckle nodules
A 34-year-old man has firm nodules on his Achilles tendons and knuckle extensor tendons. His father died of an MI at 42. LDL is 310 mg/dL; triglycerides are normal. What is the defect, and what is first-line therapy?
Tendon xanthomas with markedly elevated LDL and early family MI suggest familial hypercholesterolemia.
Statins upregulate the remaining functional receptors.
Answer. Heterozygous familial hypercholesterolemia (LDL receptor defect). Start a high-intensity statin, add ezetimibe and a PCSK9 inhibitor as needed, and screen first-degree relatives.
Straight from the Progress Note question bank, each with a cited explanation. No account needed.
123
From our NCLEX bank
A nurse preparing medications for clients notices that two products stocked next to each other have very similar names and packaging. Which action by the nurse best reduces the risk of a selection error?
Answer: C. Separating look-alike, sound-alike products and adding a tall-man-letter or warning label targets the confusion at its source, which best reduces selection errors (option C). Relying on a quick label read during a busy pass (A) is exactly the condition under which look-alike errors occur. Memorizing shelf positions (B) makes the nurse more likely to grab by habit rather than verify. Moving both products to one higher shelf (D) keeps them together and adds an access barrier without reducing confusion. Environmental and labeling strategies reduce reliance on memory and vigilance alone. The nurse also verifies the drug against the prescription at the point of care.
Source: Institute for Safe Medication Practices. (2019). ISMP list of confused drug names. Institute for Safe Medication Practices.
From our NCLEX bank
A nurse reviews the laboratory results of a client taking furosemide and finds a serum potassium of 2.9 mEq/L. Which complication should the nurse expect this client to be at greatest risk for?
Answer: A. Hypokalemia predisposes to cardiac dysrhythmias, so the nurse most closely monitors for irregular beats such as premature ventricular contractions (option A). Hyperactive reflexes and spasms (B) are associated with hypocalcemia or hyperkalemia rather than a low potassium, which causes weakness and diminished reflexes. A sustained rise in blood pressure (C) is not a typical effect of hypokalemia. A marked increase in urine output (D) is unrelated to the low potassium itself. Linking a low potassium to dysrhythmia risk guides monitoring. The nurse places the client on a cardiac monitor and anticipates potassium replacement.
A nurse teaches the client with metabolic syndrome described in the exhibit. Which teaching should the nurse prioritize to reduce cardiac risk?
Answer: B. Reducing cardiovascular risk in metabolic syndrome centers on lifestyle change, so the nurse prioritizes a heart-healthy diet, regular moderate exercise, and smoking cessation (option B). Starting rigorous marathon training immediately (A) is unsafe for a deconditioned client with cardiac risk factors. Relying only on medications without lifestyle change (C) misses the most effective interventions. Completely eliminating all dietary fat and protein (D) is neither realistic nor healthy, since the body needs some of each. Gradual, sustainable lifestyle changes lower blood pressure, glucose, and lipids. The nurse sets achievable goals with the client.
Source: Harding, M. M., Kwong, J., Hagler, D., & Reinisch, C. (2023). Lewis's medical-surgical nursing (12th ed.). Elsevier.
Your next questions are ready.
The question bank picks up from here: it adapts to what you just missed and brings it back right before you'd forget it.
What causes familial hypercholesterolemia?expand_more
Mutations in the LDL receptor (most commonly), apolipoprotein B-100, or gain-of-function PCSK9, inherited in an autosomal dominant pattern. LDL clearance falls and LDL rises markedly.
What causes eruptive xanthomas?expand_more
Very high triglycerides, as in familial chylomicronemia from lipoprotein lipase or apo C-II deficiency, or poorly controlled diabetes.
What does apolipoprotein C-II do?expand_more
It activates lipoprotein lipase, which breaks down triglycerides in chylomicrons and VLDL.
Which secondary conditions raise cholesterol?expand_more
Hypothyroidism, nephrotic syndrome, obstructive liver disease, diabetes, obesity, and drugs such as thiazides, glucocorticoids, and protease inhibitors.
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