The lipid panel, otherwise known as the cholesterol test, is one of several lab tests that your doctor may order for you as part of your routine physical. The results of a lipid panel typically include the following:
- Total Cholesterol (TC)
- Triglycerides (TG)
- HDL Cholesterol
- Estimated LDL Cholesterol
Computing the Estimated LDL Cholesterol
In lipid panel results, LDL cholesterol is usually "estimated" or "calculated". Whereas total cholesterol, triglycerides, and HDL cholesterol are cheap and easy to directly measure, the LDL cholesterol is expensive to directly measure. Because of this, the LDL cholesterol is usually provided as a number computed using the Friedewald equation:
Friedewald (1972) Formula: LDL = TC - HDL - TG/5.0 (mg/dL)
The issue with the Friedewald equation is that it is only generally accurate when Triglycerides are between 150 mg/dL and 400 mg/dL. For someone on a Paleo or a low-carb diet, the triglycerides are usually below 100 mg/dL, and in this range the Friedewald equation grossly over-estimates the LDL concentration. For cases where the triglycerides are below 100 mg/dL, a more accurate "Iranian" formula (so named since the research was conducted in Iran) has been developed:
"Iranian" (2008) Formula: LDL = TC/1.19 + TG/1.9 – HDL/1.1 – 38 (mg/dL)
Most lab reports still provide the estimated LDL cholesterol using the Friedwald equation, so it is important to compute your own estimated LDL if you and your doctor are relying on the LDL result to determine a course of treatment.
Interpreting the Results
Currently (as of 2010), of all the results you get from the lipid panel, the most significant indicator of your health risk is the ratio of triglycerides over HDL, the lower the better.
Triglycerides / HDL :
- 2 or less: ideal
- 4: average
- 6 or higher: high risk
In order to improve (reduce) the ratio, you should seek to reduce your triglycerides and increase your HDL cholesterol. Triglycerides is reduced by reducing your carbohydrate intake. HDL is increased by increasing your intake of healthy saturated fats. Both of these are fully satisfied by the Paleo diet.