What are the diagnostic criteria for hypertension?

Hypertension Diagnosis Criteria

Hypertension is diagnosed when blood pressure measured in 2-3 office visits is ≥140/90 mmHg, or when out-of-office measurements confirm elevated blood pressure with home BP ≥135/85 mmHg or 24-hour ambulatory BP ≥130/80 mmHg. 1, 2

Proper Blood Pressure Measurement Technique

Environment and Preparation

• Quiet room with comfortable temperature
• Before measurements:
  • Avoid smoking, caffeine, and exercise for 30 minutes
  • Empty bladder
  • Remain seated and relaxed for 3-5 minutes
  • No talking before, during, or between measurements

Positioning and Equipment

• Sitting position:
  • Arm resting on table with mid-arm at heart level
  • Back supported on chair
  • Legs uncrossed and feet flat on floor
• Device:
  • Use validated electronic (oscillometric) upper-arm cuff device
  • Alternatively, calibrated auscultatory device
• Cuff size:
  • Must be appropriate for arm circumference
  • Smaller cuff overestimates BP; larger cuff underestimates BP

Measurement Protocol

• Take 3 measurements with 1 minute between them
• Calculate the average of the last 2 measurements
• If first reading is <130/85 mmHg, no further measurement is required
• At first visit, measure BP in both arms simultaneously
  • If consistent difference >10 mmHg, use arm with higher BP
  • If difference >20 mmHg, consider further investigation

Diagnostic Algorithm

1. Initial Office BP Measurement:

   • If BP <130/85 mmHg → Remeasure after 3 years
   • If BP 130-139/85-89 mmHg → Take 2 more readings
   • If BP ≥140/90 mmHg → Use average of 2 readings and remeasure in 2-3 office visits

2. Confirmation of Diagnosis:

   • Repeated office BP ≥140/90 mmHg indicates hypertension
   • Confirm with out-of-office measurements when possible:
     • Home BP ≥135/85 mmHg
     • 24-hour ambulatory BP ≥130/80 mmHg

3. Special Circumstances:

   • Severe hypertension (≥180/110 mmHg) with evidence of cardiovascular disease may be diagnosed on a single visit 1
   • White coat hypertension: Elevated office BP but normal out-of-office BP
   • Masked hypertension: Normal office BP but elevated out-of-office BP

Common Pitfalls in Hypertension Diagnosis

• Single-visit diagnosis: Leads to overestimation of hypertension prevalence by approximately 12.6% 3
• Improper technique: Incorrect cuff size, patient positioning, or talking during measurement
• Ignoring BP variability: BP fluctuates throughout the day and between days
• Neglecting out-of-office measurements: Important for identifying white coat and masked hypertension
• Inadequate rest period: Not allowing sufficient time for the patient to rest before measurement

Classification of Hypertension

Category	Systolic BP	Diastolic BP
Normal	<130 mmHg	<85 mmHg
High-normal	130-139 mmHg	85-89 mmHg
Grade 1 Hypertension	140-159 mmHg	90-99 mmHg
Grade 2 Hypertension	≥160 mmHg	≥100 mmHg

The 2020 International Society of Hypertension guidelines provide this standardized classification that can be applied globally in both high and low resource settings 1, 2.