It is not widely known that there can be significant differences between the blood pressure measured in the left and right arm. The advice to doctors is that blood pressure in ALL patients should be measured in BOTH arms, particularly for patients with elevated blood pressure. The readings in both arms should be recorded, with the higher reading used for diagnosis at the initial assessment.
The arm used for the blood pressure measurement should be recorded by the doctor. Measuring blood pressure in both arms should be routine for people who monitor their blood pressure at home, and by doctors to get accurate readings for diagnosis.
Consistent differences could indicate a number of underlying health problems associated with the heart and circulation.
Blood pressure is variable throughout the day and the nervousness of patients may cause an increase in blood pressure.
In many patients the blood pressure measured by doctors and nurses is always higher. This is known as "white coat hypertension" with the higher readings triggered by nervousness and anxiety.
The readings for many people are likely to be lower when measured at home, especially first thing in the morning.
Studies suggest that 10%-20% of patients may experience white-coat syndrome.
Medical practitioners are generally well aware of 'white coat' hypertension and will take it into account before making a health diagnosis based on your blood pressure.
Generally, small differences in readings between arms isn't a health concern.
It is often due to small natural anatomical differences in the circulation.
However, a difference of more than 20 mm Hg for the high reading or more than 10 mm Hg for the bottom reading may be a sign of an underlying such as restrictions in the main arteries to that arm or other heath conditions such as kidney disease, diabetes and heart defects.
Blood pressure varies considerably with time of day, meals, coffee and other caffeinated beverages and food, smoking, anxiety, tight fitting clothing temperature, posture, and the season of the year.
It can also be affected by the way the readings are taken and cuff diameter. It is usually at its lowest during sleep and the
best time for monitoring it a home is just after waking up.
Recent research published in the Lancet journal found that significant differences need to be checked as they may be warning signs of increased risk of vascular disease and death. The differences may also be a sign of increased future risk of high blood pressure problems.
Although existing guidelines for doctors and nurses recommend that blood pressure in both arms should be measured, it is not always done.
The research study concluded that a difference in systolic blood pressure (the lower reading of 10 mm Hg) between arms were signs of increased risk of peripheral vascular disease which is the narrowing and hardening of the arteries that supply blood to the legs and feet.
A difference of 15mg Hg or more, could signify a higher risk of cerebrovascular disease and stroke, with an estimated 60% increased risk of death from all causes.
The research the findings supported the requirement that blood pressure checks in both arms should be done routinely.
It is theoretically, a quick and simple task, but some small variations are to be expected including the way the measurement is performed.
Equipment for home measurement of blood pressure using simple electronic devices has become more readily available and cheaper recently.
Recent studies have shown that home blood pressure monitoring can be accurate if measured immediately after waking in the morning, while still at rest, and before washing and dressing or eating and drinking.