Calculate the estimated upper limit of normal for Erythrocyte Sedimentation Rate based on the Miller Formula.
Male
Female
Analysis Results
Estimated Upper Limit of Normal: — mm/hr
What is the Erythrocyte Sedimentation Rate (ESR)?
The Sed Rate, or Erythrocyte Sedimentation Rate (ESR), is a common blood test used to detect inflammatory activity in the body. It measures how quickly red blood cells (erythrocytes) sink to the bottom of a tall, thin vertical tube in one hour. When inflammation is present, certain proteins cause red blood cells to clump together and fall faster.
Understanding the Miller Formula
Because the normal "speed" at which cells settle increases naturally with age, medical professionals often use the Miller Formula to estimate the maximum expected ESR for an individual. The calculations are as follows:
For Men: Age divided by 2.
For Women: (Age plus 10) divided by 2.
What Does an Elevated ESR Mean?
An ESR result higher than the calculated upper limit may indicate the presence of inflammation, but it is a non-specific test. This means it tells doctors that inflammation is occurring, but not where or why. Common causes for high ESR include:
Infections (bacterial or viral)
Autoimmune diseases (like Rheumatoid Arthritis or Lupus)
Inflammatory Bowel Disease (IBD)
Certain types of cancer
Tissue injury or trauma
Example Calculation
If a 60-year-old female takes the test, her estimated upper limit of normal would be (60 + 10) / 2 = 35 mm/hr. If her lab result is 45 mm/hr, it would be considered mildly elevated, warranting further investigation by a healthcare provider.
function calculateESR() {
var age = document.getElementById("esrAge").value;
var sex = document.getElementById("esrSex").value;
var measuredValue = document.getElementById("esrValue").value;
var resultDiv = document.getElementById("esrResult");
var limitSpan = document.getElementById("esrLimit");
var comparisonDiv = document.getElementById("esrComparison");
var statusBox = document.getElementById("esrStatusBox");
if (age === "" || age <= 0) {
alert("Please enter a valid age.");
return;
}
var ageNum = parseFloat(age);
var upperLimit = 0;
// Miller Formula
if (sex === "male") {
upperLimit = ageNum / 2;
} else {
upperLimit = (ageNum + 10) / 2;
}
// Display basic limit
limitSpan.innerText = upperLimit.toFixed(1);
resultDiv.style.display = "block";
// Handle optional measured value comparison
if (measuredValue !== "") {
var measuredNum = parseFloat(measuredValue);
comparisonDiv.innerHTML = "Your Lab Result: " + measuredNum + " mm/hr";
if (measuredNum > upperLimit) {
statusBox.innerText = "ELEVATED";
statusBox.style.backgroundColor = "#fce4e4";
statusBox.style.color = "#c0392b";
statusBox.style.border = "1px solid #c0392b";
} else {
statusBox.innerText = "WITHIN NORMAL RANGE";
statusBox.style.backgroundColor = "#e8f5e9";
statusBox.style.color = "#2e7d32";
statusBox.style.border = "1px solid #2e7d32";
}
} else {
comparisonDiv.innerHTML = "Enter a lab result value above to check if it is elevated.";
statusBox.innerText = "";
statusBox.style.border = "none";
statusBox.style.backgroundColor = "transparent";
}
// Smooth scroll to result
resultDiv.scrollIntoView({ behavior: 'smooth', block: 'nearest' });
}