TC/HDL

The TC/HDL ratio (Castelli Risk Index I) balances total cholesterol against the cholesterol-clearing HDL fraction. Lower values indicate a more favourable lipid profile; elevated values predict cardiovascular risk better than total cholesterol alone.

High ratios typically come from elevated LDL or low HDL — driven by inactivity, abdominal obesity, smoking, hypothyroidism, or refined-carbohydrate intake. Very low ratios are usually benign (very high HDL) but in rare cases reflect malnutrition or liver disease.

Elevated TC/HDL itself is silent; advanced dyslipidaemia may present as xanthelasma or tendon xanthomas.

Mediterranean pattern: olive oil, fatty fish, nuts, legumes, vegetables. Aerobic exercise raises HDL 10–15%. Plant sterols and soluble fibre (oats, psyllium) lower LDL.

Trans fats, processed meats, and full-fat dairy raise LDL while lowering HDL. Smoking materially reduces HDL.