LDL formula

I found something surprising after breaking my head over a blood test result. It seems labs don't always measure and report LDL numbers. They sometimes use a formula to compute LDL!!

If TC is Total Cholesterol and Tri is the triglyceride measurement, TC = LDL + HDL + VLDL and, as an approximation VLDL = Tri/5. That means, LDL = TC - HDL - Tri/5.
E.g., if TC is 230, HDL is 36 and Tri is 190, the LDL = 230 -36 -190/5 = 156.

Apparently, this is a close approximation in most cases where Tri is less than 400 mg/DL. In some cases, real LDL measurement could be lower. Also, higher LDL could just mean the fluffy LDL particles became larger, and not necessarily more LDL particles. Check out this link for more details - scroll down a bit to see this LDL formula stuff.

I wish labs disclose that they took a short cut to save money rather than let folks figure out or freak out! But my doctor said I need to reduce cholesterol anyways, so all this research didn't matter in the end!