Estimate your Low-Density Lipoprotein (LDL) cholesterol level using commonly available blood test results. This calculation is an estimate and should be discussed with your healthcare provider.
Your Estimated LDL Cholesterol:
— mg/dL
Understanding LDL Cholesterol and Its Calculation
Low-Density Lipoprotein (LDL) cholesterol is often referred to as "bad" cholesterol because high levels can lead to a buildup of plaque in your arteries, increasing the risk of heart disease and stroke. Monitoring your LDL levels is a crucial part of maintaining cardiovascular health.
While direct measurement of LDL is sometimes performed, it can be more complex and expensive. In many standard lipid panels, LDL cholesterol is calculated indirectly using the Friedewald equation. This equation uses the results of your Total Cholesterol, HDL Cholesterol, and Triglycerides.
The Friedewald Equation
The Friedewald equation is a widely used formula for estimating LDL cholesterol. It is expressed as follows:
Total Cholesterol: The sum of all cholesterol in your blood, including LDL, HDL, and other lipoproteins.
HDL Cholesterol: High-Density Lipoprotein, often called "good" cholesterol, which helps remove LDL from arteries.
Triglycerides: A type of fat found in your blood.
(Triglycerides / 5): This part of the equation estimates the cholesterol content carried by Very Low-Density Lipoprotein (VLDL).
How This Calculator Works
This calculator implements the Friedewald equation. You input your Total Cholesterol, HDL Cholesterol, and Triglyceride levels (typically found on a standard lipid panel blood test report). The calculator then applies the formula to provide an estimated LDL cholesterol value in milligrams per deciliter (mg/dL).
Important Considerations and Limitations
The Friedewald equation is an estimation and has certain limitations:
Triglyceride Levels: The equation is generally considered accurate when triglyceride levels are below 400 mg/dL. If your triglycerides are very high (400 mg/dL or more), this calculation may not be reliable, and a direct LDL measurement (like ultracentrifugation or precipitation methods) is preferred.
Non-Fasting Samples: While the equation can be used with non-fasting samples for Total Cholesterol and HDL, it's best to use values from a fasting lipid panel for the most accurate triglyceride reading.
Medical Advice: This calculator is for informational purposes only and does not constitute medical advice. Always consult with your healthcare provider to interpret your cholesterol results and discuss appropriate treatment or lifestyle changes. They can determine the best course of action based on your individual health profile.
Example Calculation
Let's say a patient has the following lab results:
In this example, the estimated LDL cholesterol is 123 mg/dL. This value, along with other risk factors, would be discussed with the patient's doctor.
function calculateLDL() {
var totalCholesterol = parseFloat(document.getElementById("totalCholesterol").value);
var hdlCholesterol = parseFloat(document.getElementById("hdlCholesterol").value);
var triglycerides = parseFloat(document.getElementById("triglycerides").value);
var ldlValueElement = document.getElementById("ldlValue");
// Clear previous results and error messages
ldlValueElement.textContent = "–";
// Validate inputs
if (isNaN(totalCholesterol) || isNaN(hdlCholesterol) || isNaN(triglycerides)) {
alert("Please enter valid numbers for all fields.");
return;
}
if (triglycerides >= 400) {
alert("The Friedewald equation is not accurate for triglyceride levels of 400 mg/dL or higher. Please consult your doctor for a direct LDL measurement.");
return;
}
if (totalCholesterol < hdlCholesterol) {
alert("Total Cholesterol cannot be less than HDL Cholesterol.");
return;
}
// Calculate LDL using Friedewald equation
var ldl = totalCholesterol – hdlCholesterol – (triglycerides / 5);
// Ensure LDL is not negative (can happen with very low triglycerides, though unlikely with real data)
if (ldl < 0) {
ldl = 0; // Or handle as an error, depending on desired behavior
}
// Display the result
ldlValueElement.textContent = ldl.toFixed(2); // Display with 2 decimal places
}