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Health education · Cardiovascular healthSaint‑Hyacinthe
A simple measurement that can provide additional information about your cardiovascular health.
Blood pressure is often measured on only one arm. However, during an initial assessment or in certain situations, measuring blood pressure in both arms makes it possible to check whether there is a significant difference between the right arm and the left arm.
A small difference can be normal. However, a persistent systolic pressure difference may warrant particular attention and sometimes further investigation.
Why
Blood pressure is the pressure exerted by the blood on the walls of the arteries. Measurements in both arms are generally similar, but not always identical.
The 2024 European guidelines (ESC) recommend measuring blood pressure in both arms at the initial visit in order to detect an inter-arm difference.1
Measuring both arms helps, among other things:
The threshold
The 2024 ESC guidelines define an inter-arm difference as a systolic pressure difference of more than 10 mmHg when blood pressure is measured successively in each arm.1
This does not automatically mean that a disease is present. What matters is whether the difference persists on repeated measurements, whether it is reproducible and whether it is accompanied by other signs or risk factors.
Good to know
Yes. A small difference is common. Blood pressure naturally varies from one measurement to the next depending on position, stress, movement, the time between measurements, cuff size, arm support or breathing.
A difference on a single measurement is not, on its own, enough to conclude that there is an abnormality.
A persistent difference can sometimes reflect a difference in arterial circulation. According to the ESC, a significant difference may be linked, for example, to arterial stenosis or coarctation of the aorta, which may require investigation.1
Measuring both arms remains an assessment tool, not a diagnosis on its own.
When the difference exceeds 10 mmHg, subsequent measurements are taken on the arm with the higher pressure.1
Using only the arm with the lower reading could underestimate your blood pressure and affect the diagnosis of hypertension, follow-up or treatment adjustment.
The technique
To obtain reliable results, technique is important. The ESC recommends measuring blood pressure in a seated position, after 5 minutes of rest, and avoiding exercise and stimulants such as caffeine or tobacco for at least 30 minutes beforehand.1
Blood pressure is then measured on each arm. If a difference is observed, additional measurements may be taken to check whether it persists.
You are seated with:
128 / 76 mmHg
128 — systolic pressure: the pressure in the arteries when the heart contracts and pumps blood.
76 — diastolic pressure: the pressure between beats, when the heart relaxes.
To compare the two arms, the focus is mainly on the systolic pressure difference.
Blood pressure fluctuates constantly. A single difference between the arms may simply be due to this normal variability.
Right arm 134 · Left arm 122
Here there is a 12 mmHg difference. This alone is not enough to conclude that there is vascular disease: the health professional repeats the measurements to check whether a comparable difference is consistently found.
Interpretation
No.
Several technical or physiological factors can create a temporary difference.
The assessment is based on, among other things:
To learn more
Depending on the situation, the health professional may consider:
The choice depends on age, symptoms, history and risk factors.
The ABI compares the pressure at the ankles with that in the arms. The pressure in both arms helps obtain an appropriate reference value for calculating the index.
The ABI then makes it possible to assess arterial circulation to the lower limbs.
When one arm consistently gives a higher blood pressure, it is generally the one used as the reference.
A diagnosis of hypertension should generally not be based on a single measurement. It can be confirmed by repeated measurements in the clinic, home measurements or 24-hour ambulatory blood pressure monitoring (ABPM).
Yes.
At first, ask a health professional which arm to favour. If the pressures are similar, either arm can be used consistently; if a persistent difference has been identified, the arm with the higher reading is generally preferred.
Hypertension Canada recommends, among other things, not smoking or drinking caffeine in the preceding 30 minutes, resting for 5 minutes, sitting with your back supported and feet flat, avoiding talking and taking two readings one minute apart.2
Some people must avoid measurement on one arm, for example in the presence of a dialysis fistula, after certain surgeries (including certain axillary surgeries) or in case of injury. The health professional then adapts the technique.
At Clinique IPS du Palais, our team can perform a standardized blood pressure measurement and compare the values in both arms when relevant: health assessment, NP consultation, cardiovascular assessment, ankle-brachial index, hypertension follow-up or assessment of certain symptoms.
When the results warrant it, we determine with you whether follow-up or further investigation is necessary.
Frequently asked questions
A slight difference can be normal. If the difference is significant or repeated, the health professional may take new measurements and determine whether further investigation is appropriate.
No. The arm used over the long term should ideally be determined after comparing both arms. If a persistent difference is present, the arm with the higher pressure is generally used as the reference.
A small difference can be a normal finding. What matters most is whether the difference is persistent and reproducible, rather than interpreting a single measurement in isolation.
The 2024 ESC guidelines define an inter-arm difference as a systolic pressure difference of more than 10 mmHg, measured successively in each arm. However, this alone does not constitute a diagnosis of vascular disease.
Usually not. Comparing both arms is mainly relevant during an initial assessment. Once the reference arm has been identified, it can generally be used for regular follow-up.
Measuring blood pressure in both arms is a simple step that makes it possible to determine the best arm for follow-up, avoid underestimating blood pressure, detect a persistent difference and, in certain situations, refer for a further vascular assessment.
An isolated difference should not be interpreted too quickly: the repetition and quality of measurements are essential.
The information on this page is provided for informational purposes and does not replace an assessment by a health professional.
