Calculate your Ankle Brachial Index to assess peripheral artery disease risk.
What is the Ankle Brachial Index (ABI)?
The Ankle Brachial Index (ABI) is a simple, non-invasive diagnostic test used to assess the likelihood of peripheral artery disease (PAD). PAD is a condition where narrowing of the arteries reduces blood flow to your limbs, most commonly your legs. A low ABI can indicate significant blockages in the arteries of the legs.
How is ABI Calculated?
The ABI is calculated by comparing the systolic blood pressure in your ankles to the systolic blood pressure in your arms. The formula is as follows:
ABI = (Systolic Blood Pressure in Ankle) / (Systolic Blood Pressure in Arm)
Since there are two arms and two ankles, typically the highest systolic pressure measured in each arm is averaged, and the highest systolic pressure measured in each ankle is used. The calculation is then performed for both the left and right sides:
Calculate the highest systolic blood pressure of the two ankles (e.g., if left ankle is 100 and right is 110, use 110).
Calculate the highest systolic blood pressure of the two arms (e.g., if left arm is 120 and right is 130, use 130).
Divide the higher ankle pressure by the higher arm pressure to get the ABI for that side.
The calculator above simplifies this by asking for the highest systolic pressure for the left ankle, right ankle, left arm, and right arm separately, then determines the highest ankle pressure and highest arm pressure for the calculation.
Interpreting ABI Results:
ABI > 1.40: Suggests calcified, non-compressible arteries (often seen in patients with diabetes or chronic kidney disease). This may require further investigation, but doesn't necessarily mean PAD is present.
ABI 1.00 to 1.40: Normal. No significant PAD is detected.
ABI 0.91 to 0.99: Borderline. May be considered borderline normal or mildly PAD.
ABI < 0.90: Abnormal. Suggests PAD. The lower the ABI, the more severe the PAD. An ABI below 0.50 indicates severe PAD and warrants urgent medical attention.
Why is ABI Important?
A low ABI is a strong indicator of PAD, which is a significant risk factor for:
Heart attack
Stroke
Cardiovascular death
Leg pain (claudication)
Wound healing problems
Early detection through tests like the ABI allows for timely medical intervention, lifestyle changes, and treatment to manage PAD and reduce the risk of serious complications.
Disclaimer: This calculator is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare professional for diagnosis and treatment.
function calculateABI() {
var systolicAnkleLeft = parseFloat(document.getElementById("systolicAnkleLeft").value);
var systolicAnkleRight = parseFloat(document.getElementById("systolicAnkleRight").value);
var systolicBrachialLeft = parseFloat(document.getElementById("systolicBrachialLeft").value);
var systolicBrachialRight = parseFloat(document.getElementById("systolicBrachialRight").value);
var resultDiv = document.getElementById("result");
var errorDiv = document.getElementById("errorMessage");
errorDiv.innerHTML = ""; // Clear previous errors
resultDiv.innerHTML = ""; // Clear previous results
// Input validation
if (isNaN(systolicAnkleLeft) || systolicAnkleLeft <= 0 ||
isNaN(systolicAnkleRight) || systolicAnkleRight <= 0 ||
isNaN(systolicBrachialLeft) || systolicBrachialLeft <= 0 ||
isNaN(systolicBrachialRight) || systolicBrachialRight 1.40) {
interpretation = "Suggests calcified, non-compressible arteries. Further investigation may be needed.";
} else if (abi >= 1.00 && abi = 0.91 && abi < 1.00) {
interpretation = "Borderline normal or mild PAD.";
} else if (abi < 0.90) {
interpretation = "Abnormal. Suggests PAD. Lower values indicate more severe PAD.";
}
resultDiv.innerHTML = "ABI: " + abi.toFixed(2) + "" + interpretation;
}