LDL is the one thing doctors always pay attention to when they do cholesterol blood test.
Too high and they shout you need statins.
The problem is when you are on a low carb diet like Atkins or Protein Power, after a while your triglycerides will be low while your high-density lipoprotein cholesterol (HDL) is high. The problem is LDL is expensive to measure in a laboratory, hence they generally calculate out this value using the Friedewald estimation.
ie, LDL-C (calc.) = CH − HDL − (TG/5)^2.
However this formula only works for triglycerides under 400mg/dl (4.52 mmol/l) and more importantly above 100mg/dl ( 1.13 mmol/l). When triglycerides are above 400mg/dl, the labs generally warn in the report that it cannot be calculated. But then don’t warn if its below 100mg/dl.
The problem is that if you are on low carb diet for a while, your triglycerides will naturally fall below 100mg/dl. Then then abnormal LDL will be inflated by as much as 58%.
Hence the Cholesterol Confusion
For better estimates you would use the Iranian formula from this medical paper.
Or better ask for a direct LDL measurement
Do note that you can only use this formula if TG < 100mg/dl (1.13 mmol/l) AND TC > 250mg/dl (6.46mmol/L)
For mmol/L you would use
LDL (mmol/L) = TC/1.19 + TG/0.81 – HDL/1.1 – 0.98
LDL (mg/dl) = TC/1.19 + TG/1.9 – HDL/1.1 – 38
If a doctor tries to press you to use Statins, please ask him to refer to the following articles