Ankle-Brachial Index (ABI) Calculator
Use this calculator to determine your Ankle-Brachial Index (ABI) based on your systolic blood pressure readings from your ankles and arms. The ABI is a simple, non-invasive test used to check for Peripheral Artery Disease (PAD).
Results:
Left ABI:
Right ABI:
Overall ABI Interpretation:
Understanding the Ankle-Brachial Index (ABI)
The Ankle-Brachial Index (ABI) is a quick, non-invasive test that compares the blood pressure measured at your ankle with the blood pressure measured at your arm. It's a crucial diagnostic tool primarily used to screen for Peripheral Artery Disease (PAD), a condition where narrowed arteries reduce blood flow to your limbs.
How is ABI Measured?
During an ABI test, a healthcare professional uses a standard blood pressure cuff and a Doppler ultrasound device. Blood pressure readings are taken from both ankles (dorsalis pedis and posterior tibial arteries) and both arms (brachial arteries). The highest systolic pressure from each ankle and the highest systolic pressure from either arm are used in the calculation.
The Calculation
The ABI for each leg is calculated by dividing the systolic blood pressure at the ankle by the highest systolic blood pressure from either arm. For example:
- Left ABI = Left Ankle Systolic Pressure / Highest Brachial Systolic Pressure
- Right ABI = Right Ankle Systolic Pressure / Highest Brachial Systolic Pressure
The lower of the two ABI values (left or right) is typically used for diagnostic interpretation.
Interpreting Your ABI Results
The ABI value helps classify the severity of potential PAD:
- 1.0 – 1.4: Normal ABI – Indicates no significant narrowing of the arteries.
- 0.91 – 0.99: Borderline ABI – Suggests a possible mild narrowing; further evaluation might be recommended.
- 0.70 – 0.90: Mild PAD – Indicates mild peripheral artery disease.
- 0.40 – 0.69: Moderate PAD – Indicates moderate peripheral artery disease.
- < 0.40: Severe PAD – Indicates severe peripheral artery disease, often associated with critical limb ischemia.
- > 1.4: Non-compressible arteries – This high reading can occur in individuals with diabetes or severe arterial calcification, where the arteries are stiff and cannot be compressed. In such cases, other tests like toe-brachial index (TBI) may be needed.
Why is ABI Important?
An abnormal ABI can be an early indicator of PAD, even before symptoms like leg pain (claudication) appear. Early detection allows for lifestyle modifications, medication, and other interventions to manage the condition and reduce the risk of serious complications, including heart attack, stroke, and limb loss.
It's important to remember that this calculator provides an estimate based on your inputs. Always consult with a healthcare professional for an accurate diagnosis and personalized medical advice regarding your ABI results.