Estimate LDL from a lipid panel.
Most lipid panels do not measure LDL directly; they calculate it with the Friedewald equation, which subtracts HDL and an estimate of VLDL from total cholesterol. VLDL is approximated as triglycerides divided by five, a ratio that holds in fasting samples with normal triglycerides but breaks down above roughly 400 mg/dL, where a direct LDL assay is required instead.
Friedewald equation
LDL = total cholesterol - HDL - (triglycerides / 5)
Non-HDL cholesterol
Non-HDL = total cholesterol - HDL
Educational estimate only. Not medical advice — discuss results with a qualified clinician before changing treatment, medication or exercise.
The fixed divide-by-five ratio assumes a normal triglyceride-to-cholesterol composition in VLDL. Above 400 mg/dL that assumption fails and the equation systematically underestimates LDL.
Yes for Friedewald, because the triglyceride term is fasting-dependent. Non-HDL cholesterol works on a non-fasting sample, which is one reason it is increasingly preferred.