Atherogenic Index Calculator

Total cholesterol tells you the total mass of cholesterol in your blood. The atherogenic index tells you how much of it is likely to clog your arteries. The calculator for the atherogenic index of plasma (AIP) computes log(triglycerides/HDL) — a metric that captures the balance between pro-atherogenic (TG-rich) and anti-atherogenic (HDL) lipoprotein fractions, providing cardiovascular risk discrimination that individual lipid values miss.

The AIP Formula

The atherogenic index of plasma is defined as:

AIP = log₁₀(Triglycerides / HDL-C)

where both triglycerides and HDL-C are in mmol/L. For values in mg/dL, convert first: mmol/L = mg/dL / 88.57 for TG, and mg/dL / 38.67 for HDL. Example: TG = 150 mg/dL = 1.695 mmol/L; HDL = 50 mg/dL = 1.293 mmol/L; AIP = log₁₀(1.695/1.293) = log₁₀(1.311) = 0.118. Interpretation: intermediate risk range. This online calculator accepts both mg/dL and mmol/L and applies the conversion automatically. The cholesterol ratio calculator provides related lipid panel ratios including the TC/HDL and LDL/HDL ratios.

AIP Risk Categories

Published thresholds from validation studies (Dobiasova et al.):

• AIP below −0.3: low cardiovascular risk; anti-atherogenic lipid profile
• AIP −0.3 to 0.1: intermediate low risk
• AIP 0.1 to 0.24: intermediate risk; monitoring warranted
• AIP above 0.24: high cardiovascular risk; significant atherogenic lipid profile; clinical attention recommended

AIP is particularly valuable in patients with metabolic syndrome, diabetes, and insulin resistance — conditions where TG is elevated and HDL is depressed — because traditional lipid metrics (LDL-C) may appear normal while actual atherogenic burden is high.

Why TG/HDL Ratio Reflects Atherogenicity

The TG/HDL ratio is a powerful surrogate for small dense LDL (sdLDL) particle concentration — the most atherogenic LDL subclass. Small dense LDL particles are produced in conditions of triglyceride excess: they enter the arterial intima more readily than large buoyant LDL, are more susceptible to oxidation, bind poorly to LDL receptors, and have longer circulation time. HDL, simultaneously reduced in hypertriglyceridemic states, is responsible for reverse cholesterol transport from the arterial wall. High TG + low HDL = high sdLDL particle burden + impaired reverse cholesterol transport = high atherogenicity regardless of total LDL-C. A patient with TG = 300 mg/dL and HDL = 35 mg/dL may have LDL-C = 100 mg/dL (seemingly acceptable) but AIP = 0.40 (high risk), reflecting a pathological sdLDL-predominant pattern.

AIP vs. Other Cardiovascular Risk Metrics

The AIP complements rather than replaces other cardiovascular risk tools:

• AIP advantage: captures atherogenic dyslipidemia (high TG, low HDL) that traditional LDL-C misses; useful in metabolic syndrome screening
• Limitation: not yet incorporated into major guideline risk equations (ACC/AHA, ESC); evidence base smaller than Framingham or Pooled Cohort Equations
• Complementary use: AIP is most useful as an additional risk marker in patients with borderline ACC/AHA ASCVD risk (5–20%) where it can reclassify risk upward and support statin initiation decisions

The LDL calculator and lipid and cholesterol calculators provide the complete lipid analysis toolkit.