Is a 6mmHg Systolic Blood Pressure Difference Between Arms Concerning?
A 6mmHg systolic blood pressure difference between arms is not concerning and falls well within the normal range of physiological variation that occurs in healthy individuals.
Understanding Normal Inter-Arm Blood Pressure Variation
The evidence clearly demonstrates that small inter-arm blood pressure differences are physiologically normal and expected:
Mean absolute differences in healthy populations range from 5.4-6.3 mmHg for systolic blood pressure, which means your 6mmHg difference is entirely typical 1, 2.
The American Heart Association guidelines note that while differences between arms are commonly found, there is no systematic pattern, and approximately 20% of normal individuals have differences exceeding 10mmHg 3.
In a large study of ambulatory patients without cardiovascular disease, 83.8% of men and 89.6% of women had inter-arm systolic differences of ≤6mmHg, confirming this is the normal range 4.
When Inter-Arm Differences Become Clinically Significant
The threshold for concern is substantially higher than 6mmHg:
Differences ≥10mmHg warrant attention and repeat measurement to confirm reproducibility, as this occurs in about 20% of the population and may indicate underlying vascular pathology 3, 1.
Differences ≥15mmHg are associated with increased cardiovascular risk in patients without manifest vascular disease and should prompt vascular evaluation 5.
Differences ≥20mmHg are strongly suggestive of significant vascular pathology such as subclavian artery stenosis, aortic dissection, or large vessel vasculitis and require urgent evaluation 6, 7.
Clinical Implications for Your 6mmHg Difference
Your 6mmHg difference requires no specific action beyond standard practice:
No further workup is needed for this magnitude of difference in the absence of other concerning symptoms 1, 4.
Use the arm with the higher reading for ongoing blood pressure monitoring to avoid underestimating blood pressure 6, 7.
The difference is likely due to normal physiological variation in arterial stiffness and geometry between arms rather than pathology 8.
Common Pitfalls to Avoid
When interpreting inter-arm blood pressure differences:
Ensure proper measurement technique was used, including both arms positioned at heart level, appropriate cuff sizes, and the patient's back supported 3.
Arm position errors can create artificial differences of 10mmHg or more (2mmHg for every inch above or below heart level), so technique matters more than small numerical differences 3.
Don't dismiss large differences (≥20mmHg) as normal variation without proper evaluation, as this represents a critical pitfall that can miss serious vascular pathology 6.