When to Take Home Blood Pressure Readings
Home blood pressure should be measured twice daily—once in the morning before medications and breakfast (but not immediately after awakening) and once in the evening—with two readings per session separated by 1-2 minutes, for 7 consecutive days, excluding the first day's readings from your final average. 1, 2, 3
Timing Protocol
Daily Measurement Schedule
- Morning readings: Take before breakfast and before taking antihypertensive medications, but allow time after awakening to avoid the immediate post-awakening surge 1
- Evening readings: Take before dinner, typically in the early evening 1, 4
- Frequency: Two readings at each session (morning and evening), separated by 1-2 minutes 1, 3, 4
Duration of Monitoring
- Standard protocol: Measure for 7 consecutive days 1, 3, 5
- Minimum acceptable: 3 days if time-constrained, though 7 days provides greater reliability 1, 6
- Critical detail: Discard all readings from the first day, as they are systematically higher and less reliable 2, 3
- Final calculation: Average all readings from days 2-7, yielding 12 total readings (6 days × 2 sessions per day) for clinical decisions 1, 2
Pre-Measurement Preparation
Essential Steps Before Each Reading
- Empty your bladder before measuring 1, 3
- Avoid caffeine, tobacco, and exercise for 30 minutes before measurement 1, 3, 4
- Rest quietly for 5 minutes in a seated position 1, 3, 4
- Sit with back supported, feet flat on floor (uncrossed), and arm supported at heart level 1, 3, 4
- Remain silent during the entire measurement 3
When to Extend Monitoring
If your 3-day average is close to the treatment threshold (near 135/85 mmHg), continue measuring for the full 7 days for greater precision. 1, 7
Clinical Context for Your Patient
For a patient with hypertension, smoking history, and likely hyperlipidemia:
- Routine monitoring: Measure for 3-7 days a few weeks after initiating or changing medications and before clinic visits 1
- Not daily forever: You do not need to measure blood pressure every single day indefinitely—periodic monitoring windows are sufficient 1
- Masked hypertension risk: Patients with cardiovascular risk factors (smoking, hyperlipidemia) have higher rates of masked hypertension, making home monitoring particularly valuable 1
Diagnostic Thresholds
- Hypertension: Average home BP ≥135/85 mmHg 1, 3, 5
- Elevated BP: 120-134/70-84 mmHg 1, 3
- Normal: <120/70 mmHg 3
Common Pitfalls to Avoid
- Don't include first day readings: This is the most commonly missed detail and leads to overdiagnosis of hypertension 2
- Don't measure immediately after awakening: Allow time for the post-awakening BP surge to settle 1
- Don't take readings only when you "feel off": This introduces selection bias; stick to the scheduled morning and evening times 1
- Don't use devices older than 4 years: They may be inaccurate and should be replaced 1