Estimate your LDL Cholesterol using the Friedewald formula.
Your Estimated LDL Cholesterol
— mg/dL
Understanding LDL Cholesterol and the Friedewald Formula
Low-Density Lipoprotein (LDL) cholesterol, often referred to as "bad" cholesterol, plays a crucial role in cardiovascular health. High levels of LDL can lead to the buildup of plaque in arteries, increasing the risk of heart disease, heart attack, and stroke. Monitoring and managing your LDL cholesterol levels is an essential part of maintaining a healthy lifestyle.
The Friedewald formula is a widely used method for estimating LDL cholesterol levels from a standard lipid panel. This formula is particularly useful because it allows for the calculation of LDL without requiring a direct laboratory measurement, which can sometimes be more costly or less readily available.
How the Friedewald Formula Works:
The formula is based on the principle that total cholesterol is the sum of different types of cholesterol and triglycerides. Specifically:
Very Low-Density Lipoprotein (VLDL) cholesterol is not typically measured directly. However, VLDL cholesterol can be estimated from triglyceride levels using the following approximation:
VLDL Cholesterol ≈ Triglycerides / 5 (when triglycerides are in mg/dL)
By substituting this into the first equation and rearranging, we get the Friedewald formula for estimating LDL Cholesterol:
Accuracy: The Friedewald formula is an estimation and is most accurate when triglyceride levels are below 400 mg/dL. At higher triglyceride levels, the estimation becomes less reliable.
Non-Fasting Sample: The formula is generally more accurate with a fasting blood sample, as recent food intake can temporarily elevate triglyceride levels.
Other Lipoproteins: The formula assumes a specific relationship between triglycerides and VLDL, which may not hold true for everyone, especially individuals with certain metabolic conditions.
Consult Your Doctor: This calculator is for informational purposes only and should not replace professional medical advice. Always consult with your healthcare provider to interpret your lipid panel results and discuss appropriate management strategies.
Example Calculation:
Let's consider a patient with the following lipid panel results:
In this example, the estimated LDL cholesterol level is 129 mg/dL.
function calculateLDL() {
var totalCholesterol = parseFloat(document.getElementById("totalCholesterol").value);
var hdlCholesterol = parseFloat(document.getElementById("hdlCholesterol").value);
var triglycerides = parseFloat(document.getElementById("triglycerides").value);
var resultValueElement = document.getElementById("result-value");
var resultNoteElement = document.getElementById("result-note");
// Clear previous results and notes
resultValueElement.textContent = "– mg/dL";
resultNoteElement.textContent = "";
// Input validation
if (isNaN(totalCholesterol) || isNaN(hdlCholesterol) || isNaN(triglycerides)) {
resultNoteElement.textContent = "Please enter valid numbers for all fields.";
return;
}
if (triglycerides >= 400) {
resultNoteElement.textContent = "The Friedewald formula is less accurate when triglycerides are 400 mg/dL or higher. Direct measurement is recommended.";
}
if (totalCholesterol < hdlCholesterol) {
resultNoteElement.textContent = "Total Cholesterol cannot be less than HDL Cholesterol. Please check your inputs.";
return;
}
if (hdlCholesterol <= 0) {
resultNoteElement.textContent = "HDL Cholesterol must be a positive value.";
return;
}
if (totalCholesterol <= 0) {
resultNoteElement.textContent = "Total Cholesterol must be a positive value.";
return;
}
// Calculate LDL using Friedewald formula
var ldlEstimate = totalCholesterol – hdlCholesterol – (triglycerides / 5);
// Ensure LDL is not negative (though unlikely with valid inputs)
if (ldlEstimate < 0) {
ldlEstimate = 0; // LDL cannot be negative
}
resultValueElement.textContent = ldlEstimate.toFixed(2) + " mg/dL";
// Add interpretation based on general guidelines (these are general and can vary)
var interpretation = "";
if (ldlEstimate = 100 && ldlEstimate = 130 && ldlEstimate = 160 && ldlEstimate = 190
interpretation = "This is very high.";
}
resultNoteElement.textContent = "Estimated LDL: " + ldlEstimate.toFixed(2) + " mg/dL. Interpretation: " + interpretation + " (Consult your doctor for personalized advice).";
}