Lipid Disorders

Lipid Disorders

Lipid disorders (dyslipidemias) are abnormalities in plasma lipid levels. They are major risk factors for cardiovascular disease (CVD) — the leading cause of death worldwide.

Hyperlipoproteinemias (Fredrickson Classification)

  • Type I: ↑Chylomicrons. LPL or ApoC-II deficiency. Presents: Pancreatitis, eruptive xanthomas, creamy plasma. No ↑CVD risk. Treatment: Very low fat diet.
  • Type IIa (Familial Hypercholesterolemia): ↑LDL only. LDL receptor mutation (autosomal dominant). Presents: Tendon xanthomas (Achilles), xanthelasma, premature CAD. Treatment: Statins, PCSK9 inhibitors.
  • Type IIb: ↑LDL + ↑VLDL. Combined hyperlipidemia. High CVD risk.
  • Type III: ↑IDL (remnant particles). ApoE2/E2 homozygosity. Palmar xanthomas, premature CAD. Treatment: Fibrates, Statins.
  • Type IV: ↑VLDL (endogenous hypertriglyceridemia). Associated with obesity, DM, alcohol. ↑Pancreatitis risk. Treatment: Fibrates, Niacin, lifestyle.
  • Type V: ↑Chylomicrons + ↑VLDL. Severe hypertriglyceridemia; pancreatitis risk.

Atherosclerosis

Atherosclerosis is the underlying process of coronary artery disease, stroke, and peripheral artery disease. Pathogenesis: Endothelial injury (hypertension, smoking, hyperglycemia) → LDL accumulation in intima → oxidation → foam cell formation (macrophages engulf oxLDL) → Fatty streak → Fibrous plaque → Complicated plaque (ulceration, thrombosis, calcification).

  • Risk factors: ↑LDL, ↓HDL, hypertension, diabetes, smoking, obesity, family history
  • Reverse cholesterol transport (HDL) is protective
  • Lipoprotein(a) [Lp(a)]: Independent CVD risk factor; structurally similar to LDL with ApoA attached to ApoB

Fatty Liver Disease (Hepatic Steatosis)

Accumulation of TG in hepatocytes (>5% of liver weight).

  • NAFLD/NASH: Non-alcoholic fatty liver disease; associated with obesity, insulin resistance, metabolic syndrome
  • Alcoholic Fatty Liver: Alcohol → ↑NADH/NAD+ ratio → ↓FAO + ↑FA synthesis + ↑TG synthesis → steatosis; VLDL export impaired
  • Can progress: Steatosis → Steatohepatitis → Fibrosis → Cirrhosis → HCC

Treatment of Dyslipidemias

  • Statins (HMG-CoA Reductase inhibitors): First-line for ↑LDL. Also anti-inflammatory effects.
  • Fibrates (PPAR-α agonists): Best for ↑TG (↑LPL activity, ↓VLDL production). Fenofibrate, Gemfibrozil.
  • Niacin (B3): ↑HDL most effectively; ↓TG, ↓LDL. Side effects: Flushing (PGE-mediated). ↑Uric acid.
  • Bile acid sequestrants: Cholestyramine; bind bile acids in gut → ↓recycling → liver converts cholesterol to bile acids → ↓LDL. Constipation; may ↑TG.
  • Ezetimibe: Blocks intestinal NPC1L1 transporter → ↓cholesterol absorption → ↓LDL. Used with statins.
  • PCSK9 inhibitors: Monoclonal antibodies (Evolocumab, Alirocumab); greatly ↓LDL (up to 60%) by preventing LDL receptor degradation.

Sphingolipidoses (Lysosomal Storage Diseases)

  • Gaucher's (Glucocerebrosidase def.) — Most common; bone, spleen, liver
  • Niemann-Pick (Sphingomyelinase def.) — Foam cells, cherry-red spot
  • Tay-Sachs (Hexosaminidase A def.) — GM2 gangliosidosis; cherry-red spot, neurodegeneration; no organomegaly
  • Fabry's (α-Galactosidase A def.) — X-linked; kidney failure, painful neuropathy, skin lesions (angiokeratomas)
  • Krabbe's (Galactocerebrosidase def.) — White matter; globoid cells; infantile onset

Quiz - Exam Preparation Strategy

When studying Quiz for your final board exams, it is critical to focus on the core concepts and fundamental formulas. Relying strictly on NCERT textbook solutions and practicing previous year questions (PYQs) is the proven methodology for scoring high marks. Avoid rote memorization and instead focus on the logical application of the theories presented in this chapter.

⚠️ Common Mistakes to Avoid

❓ Frequently Asked Questions

How can I quickly memorize the concepts of Quiz?

The most effective way is to create short, handwritten revision notes and continuously test your knowledge using our interactive Mock Tests. Spaced repetition and active recall are much better than passive reading.

What type of questions are most commonly asked from Quiz?

Board exams tend to favor conceptual application questions and direct formula-based derivations from the NCERT syllabus. Ensure you have solved every single exercise in the official textbook.

Is reading the NCERT book enough for this chapter?

Yes, the NCERT textbook is the absolute gold standard for board exams. However, to improve your speed and accuracy during the actual exam, you must supplement your reading by solving timed mock tests and objective questions.