What are the diagnostic criteria for hypertension?

Diagnosing Hypertension

Hypertension is diagnosed when office blood pressure is ≥140/90 mmHg confirmed on multiple separate visits, or when out-of-office measurements show home BP ≥135/85 mmHg or 24-hour ambulatory BP ≥130/80 mmHg. 1, 2

Blood Pressure Measurement Technique

Use a validated automated oscillometric upper-arm cuff device with appropriate cuff size for the individual patient. 1, 2

• The patient must sit quietly in a chair with feet flat on the floor and back supported for at least 5 minutes before measurement 2
• Support the patient's arm at heart level (midpoint of sternum) during measurement 2
• The cuff bladder should encircle 75-100% of the arm circumference 2
• At each visit, record three BP measurements 1-2 minutes apart 1
• If the first two readings differ by >10 mmHg, perform additional measurements 1
• The patient's BP is the average of the last two readings 1

Diagnostic Criteria Based on BP Level

Grade 1 Hypertension (140-159/90-99 mmHg)

Confirm the diagnosis over several months using repeated office measurements on at least 2-3 separate visits. 1, 2

• Out-of-office confirmation with home BP monitoring or 24-hour ambulatory monitoring is strongly recommended before initiating treatment 1, 3
• Home BP ≥135/85 mmHg confirms hypertension 1, 2
• 24-hour ambulatory BP ≥130/80 mmHg confirms hypertension 1, 2

Grade 2 Hypertension (160-179/100-109 mmHg)

Confirm the diagnosis as soon as possible (within 1 month), preferably using home or ambulatory BP measurements. 1

• If out-of-office monitoring is not feasible, confirm with repeated office measurements over weeks rather than months 1, 2
• Patients with evidence of organ damage or high cardiovascular risk require measurements over shorter periods (days to weeks) 1, 2

Grade 3 Hypertension (≥180/110 mmHg)

First exclude hypertensive emergency by assessing for acute end-organ damage. 1

• In severe cases with evidence of cardiovascular disease, diagnosis can be made on a single visit 2
• If BP ≥180/110 mmHg without acute end-organ damage (hypertensive urgency), confirm diagnosis promptly but can be managed as outpatient 4

Out-of-Office BP Confirmation

Out-of-office measurements should be used whenever logistically and economically feasible to confirm the diagnosis. 1

Home Blood Pressure Monitoring

• Hypertension confirmed when home BP ≥135/85 mmHg 1, 2
• Multiple measurements over several days provide more accurate assessment than office readings alone 1

24-Hour Ambulatory Blood Pressure Monitoring

• Hypertension confirmed when 24-hour ambulatory BP ≥130/80 mmHg 1, 2
• Particularly useful for detecting white-coat hypertension and masked hypertension 1

Special Measurement Considerations

Measure BP in both arms simultaneously at the first visit; use the arm with consistently higher readings for subsequent measurements. 1

Measure standing BP after 1 minute and again after 3 minutes in specific populations: 2

• All treated hypertensive patients at follow-up visits
• Patients with symptoms suggesting postural hypotension
• Elderly patients at first visit
• Patients with diabetes at first visit

Common Pitfalls to Avoid

Do not diagnose hypertension based on a single office visit unless BP is severely elevated (≥180/110 mmHg) with evidence of acute end-organ damage. 2

• Blood pressure has large spontaneous variations throughout the day, between days, and across seasons 1
• Single-visit diagnosis leads to significant overestimation of true hypertension prevalence by approximately 12.6% 5
• Unconfirmed cases on single evaluation often do not meet criteria on reassessment 5

Avoid using non-validated devices or incorrect cuff sizes, as these lead to inaccurate measurements. 1, 2