Which of the following formulas is used to calculate LDL cholesterol?

The correct formula for calculating LDL (low-density lipoprotein) cholesterol is based on the Friedewald equation, which is primarily used for estimating LDL cholesterol levels when triglyceride concentrations are below 400 mg/dL. The formula is expressed as:

LDL cholesterol = total cholesterol - HDL cholesterol - (triglycerides/5).

In this formula, total cholesterol represents the overall cholesterol in the blood, HDL cholesterol is the high-density lipoprotein cholesterol, which is often referred to as the "good" cholesterol, and triglycerides are another type of fat found in the blood. The division by 5 is a conversion factor to estimate the LDL cholesterol, as triglycerides are converted into their very low-density lipoprotein (VLDL) cholesterol equivalents.

This formula is critical since it provides healthcare professionals with an important metric to assess cardiovascular risk. A higher level of LDL cholesterol is associated with an increased risk of atherosclerosis and cardiovascular disease, making this calculation particularly significant in clinical practice.

Other options do not accurately reflect this relationship or the correct mathematical arrangement of the components, which is essential for obtaining a reliable estimate of LDL cholesterol levels.