Healthcare & Clinical Calculations
Sampson-NIH Equation 2 LDL Cholesterol Calculator (TG up to 800 mg/dL)
Calculate beta-quantification-calibrated LDL cholesterol (mg/dL) up to triglycerides of 800 mg/dL using Maureen Sampson’s bivariate NIH Equation 2 and measure Friedewald underestimation bias.
Stop Friedewald’s TG / 5 assumption from under-treating high-triglyceride ASCVD patients!
Since 1972, clinical labs estimated LDL cholesterol via William Friedewald’s fixed-ratio formula LDL = TC - HDL - (TG / 5), which assumes VLDL always carries a 5:1 triglyceride-to-cholesterol mass ratio. When triglycerides rise into the 200–800 mg/dL range (or when PCSK9 inhibitors drive LDL below 70 mg/dL), chylomicron/VLDL remnants become triglyceride-enriched, so TG / 5 overestimates VLDL-C and falsely underestimates atherogenic LDL-C—leaving high-risk cardiovascular patients under-treated!
Maureen Sampson et al. at the National Institutes of Health (JAMA Cardiology 2020) calibrated a bivariate quadratic least-squares equation against gold-standard ultracentrifugation beta-quantification valid all the way up to TG = 800 mg/dL: LDL_Sampson = (TC / 0.948) - (HDL / 0.971) - ((TG / 8.56) + ((TG * NonHDL) / 2140) - (TG^2 / 16100)) - 9.44, where NonHDL = TC - HDL! For TC = 210, HDL = 42, TG = 280 mg/dL, Friedewald reports 112.0 mg/dL, whereas Sampson-NIH reveals the true 119.0 mg/dL (+7.0 mg/dL higher atherogenic burden)!
| Lipid Panel Scenario (mg/dL) | Classical Friedewald LDL | Sampson-NIH Equation 2 LDL | Clinical Discordance |
|---|---|---|---|
| Hypertriglyceridemia (TC 210, HDL 42, TG 280) | 112.0 mg/dL | 119.0 mg/dL | +7.0 mg/dL Masked by Friedewald |
| Normotriglyceridemic (TC 185, HDL 55, TG 110) | 108.0 mg/dL | 110.3 mg/dL | +2.3 mg/dL Close Agreement |
| Extreme Chylomicronemia (TG > 800 mg/dL) | Invalid (> 400 Cutoff) | "Direct Beta-Quantification Required" | Exceeds 800 mg/dL NIH Limit |
Sampson-NIH Equation 2 Estimated LDL-C (mg/dL, Valid for TG <= 800)
Evaluates (TC/0.948) - (HDL/0.971) - ((TG/8.56) + (TG*(TC-HDL))/2140 - (TG^2)/16100) - 9.44 while guarding TG > 800 mg/dL.
=IF(OR(B2 <= B3, B3 <= 0, B4 <= 0, B4 > 800), "Direct Beta-Quantification Required (TG > 800 or Invalid Lipids)", ROUND((B2 / 0.948) - (B3 / 0.971) - ((B4 / 8.56) + ((B4 * (B2 - B3)) / 2140) - ((B4 ^ 2) / 16100)) - 9.44, 1))Sampson-NIH Minus Classical Friedewald LDL Difference (mg/dL)
Quantifies how many mg/dL of LDL-C classical Friedewald (TC - HDL - TG/5) underestimates at elevated triglycerides.
=IF(OR(B2 <= B3, B3 <= 0, B4 <= 0, B4 > 800), "Direct Beta-Quantification Required (TG > 800 or Invalid Lipids)", ROUND(((B2 / 0.948) - (B3 / 0.971) - ((B4 / 8.56) + ((B4 * (B2 - B3)) / 2140) - ((B4 ^ 2) / 16100)) - 9.44) - (B2 - B3 - (B4 / 5)), 1))Try the example
Use the original values or change them to test your understanding.