What is Cholesterol?

Cholesterol is a sterol (lipid molecule) that is:

• An essential component of cell membranes

• Precursor of steroid hormones

• Precursor of bile acids

• Required for vitamin D synthesis

It is transported in blood via lipoproteins:

• LDL (Low-Density Lipoprotein)

• HDL (High-Density Lipoprotein)

• VLDL

Normal Reference Range (Total Cholesterol)

• Desirable: < 200 mg/dL

• Borderline high: 200–239 mg/dL

• High: ≥ 240 mg/dL

Clinical Significance

1️⃣ Cardiovascular Disease (CVD)

Elevated total cholesterol, especially LDL-C, is associated with:

• Coronary artery disease

• Myocardial infarction

• Stroke

• Peripheral vascular disease

Mechanism:

• LDL deposits cholesterol in arterial walls

• Leads to atherosclerotic plaque formation

2️⃣ Hypercholesterolemia

Causes:

Primary (Genetic):

• Familial hypercholesterolemia

• Familial combined hyperlipidemia

Secondary:

• Hypothyroidism

• Nephrotic syndrome

• Obstructive jaundice

• Diabetes mellitus

3️⃣ Hypocholesterolemia

Less common.

Seen in:

• Hyperthyroidism

• Malnutrition

• Severe liver disease

• Chronic infections

• Malabsorption

4️⃣ Liver Disease

Cholesterol levels may:

• Increase in obstructive jaundice

• Decrease in severe hepatocellular failure

5️⃣ Nephrotic Syndrome

• Elevated cholesterol due to increased hepatic lipoprotein synthesis

• Part of nephrotic dyslipidemia

6️⃣ Endocrine Disorders

• ↑ in hypothyroidism

• ↓ in hyperthyroidism

• Altered in Cushing’s syndrome

7️⃣ Xanthomas & Arcus Senilis

Chronic hypercholesterolemia may cause:

• Tendon xanthomas

• Xanthelasma

• Corneal arcus