What is the measurement for high blood pressure?

High Blood Pressure Measurement

High blood pressure (hypertension) is defined as blood pressure readings consistently at or above 130/80 mmHg according to the most recent American College of Cardiology/American Heart Association guidelines. 1

Blood Pressure Classifications

According to the 2017 ACC/AHA guidelines, blood pressure is classified as follows:

• Normal: <120/<80 mmHg
• Elevated: 120-129/<80 mmHg
• Stage 1 Hypertension: 130-139/80-89 mmHg
• Stage 2 Hypertension: ≥140/90 mmHg 1, 2

This represents a significant change from previous guidelines (JNC 7) which defined hypertension as ≥140/90 mmHg. The reclassification was based on evidence showing increased cardiovascular risk beginning at lower blood pressure levels.

Proper Measurement Technique

Accurate blood pressure measurement is crucial for proper diagnosis and requires:

• Using a properly calibrated and validated device
• Patient seated comfortably for 5 minutes before measurement
• Arm supported at heart level
• Appropriate cuff size (covering 80% of arm circumference)
• Taking the mean of at least two readings
• Avoiding talking during measurement 1

Special Considerations

Out-of-Office Measurements

• Home BP monitoring: Threshold for hypertension is >135/85 mmHg
• Ambulatory BP monitoring: 24-hour average threshold is >125/80 mmHg 1

Types of Hypertension

1. Isolated Systolic Hypertension: Systolic BP ≥140 mmHg with diastolic BP <90 mmHg (common in older adults) 1

2. Isolated Diastolic Hypertension: Systolic BP <140 mmHg with diastolic BP ≥90 mmHg (more common in younger adults) 1

3. White Coat Hypertension: Elevated BP in clinical settings (≥140/90 mmHg) but normal BP at home (<135/85 mmHg) 1

4. Masked Hypertension: Normal BP in clinical settings but elevated BP outside clinical settings 1

Clinical Significance

The health risks associated with hypertension begin at 115/75 mmHg and double with each 20/10 mmHg increase. Hypertension significantly increases the risk of:

• Stroke
• Myocardial infarction
• Heart failure
• Chronic kidney disease
• Premature mortality 3

Monitoring Recommendations

• Adults with normal BP (<120/80 mmHg): Recheck at least every 5 years
• Adults with elevated BP (120-129/<80 mmHg): Recheck annually
• Adults with "high normal" BP (130-139/85-89 mmHg): Recheck annually 1

Common Pitfalls in Blood Pressure Measurement

• Improper cuff size: Too small a cuff can falsely elevate readings by 10-40 mmHg
• Talking during measurement: Can increase readings by 10-15 mmHg
• Unsupported arm: Can increase readings by 10 mmHg
• Full bladder: Can increase readings by 10-15 mmHg
• Recent caffeine, smoking, or exercise: Can temporarily elevate readings
• Single reading: BP naturally varies; multiple readings provide more accurate assessment 1

Understanding the correct definition and measurement of high blood pressure is essential for proper diagnosis and management to reduce cardiovascular morbidity and mortality.