Which of the following pre-measurement factors can artificially elevate BP readings?

• A. Measuring in a warm room
• B. Caffeine or nicotine intake within 30 minutes prior to measurement
• C. Having a full bladder
• D. Recent physical activity

Answer: (B)

Recent stimulant intake can skew BP readings upward. Caffeine and nicotine act quickly to raise blood pressure: caffeine blocks adenosine receptors, which increases sympathetic activity and catecholamine release, causing vasoconstriction and a higher heart rate and cardiac output. Nicotine similarly triggers adrenaline release and sympathetic tone, also leading to vasoconstriction. Taken within about 30 minutes of measurement, these effects can artificially elevate the reading, which is why this factor is the best answer.

The other factors don’t reliably produce the same consistent, short-term elevation. A warm room tends to promote vasodilation and may not raise BP in the same way, a full bladder can cause discomfort but doesn’t reliably elevate reading, and physical activity raises BP acutely but guidelines emphasize resting before measurement to avoid that effect.