Diagnosing Hypertension
The diagnosis of hypertension requires blood pressure measurements ≥130/80 mmHg based on an average of two or more measurements obtained on two or more occasions. 1
Office Blood Pressure Measurement Protocol
- Blood pressure should be measured at every routine clinical visit in a quiet room with comfortable temperature 2
- Patient preparation is essential: avoid smoking, caffeine, and exercise for 30 minutes before measurement 2
- Patients should empty their bladder and remain seated with back supported, legs uncrossed, and feet flat on the floor for 3-5 minutes before measurement 2
- The arm should be supported at heart level with an appropriately sized cuff (bladder should cover 75-100% of arm circumference) 1
- Take 3 measurements with 1 minute between them and calculate the average of the last 2 measurements 1
- If the first reading is <130/85 mmHg, no further measurement is required 1
- Initially, measure blood pressure in both arms; if there is a consistent difference >10 mmHg, use the arm with the higher blood pressure 1
Confirming the Diagnosis
- For individuals with elevated blood pressure (systolic 120-129 mmHg and diastolic <80 mmHg), confirm using multiple readings, including measurements on a separate day 1
- Hypertension is defined as systolic blood pressure ≥130 mmHg or diastolic blood pressure ≥80 mmHg 1
- The diagnosis should be based on an average of ≥2 measurements obtained on ≥2 occasions 1
- For blood pressure 140-159/90-99 mmHg, diagnosis should preferably be confirmed using out-of-office measurements 1
- Individuals with blood pressure ≥180/110 mmHg and cardiovascular disease could be diagnosed with hypertension at a single visit 1
Out-of-Office Blood Pressure Measurement
- All people with hypertension should monitor their blood pressure at home after appropriate education 1
- Out-of-office measurements are more reproducible than office measurements and more closely associated with hypertension-induced organ damage 1
- Home blood pressure monitoring (HBPM) and 24-hour ambulatory blood pressure monitoring (ABPM) help identify white coat and masked hypertension 1
- For HBPM, take at least 2 morning and 2 evening readings every day for 1 week but discard the readings of the first day (total of 12 readings) 1
- Thresholds for hypertension diagnosis:
Blood Pressure Classification
| Category | Systolic BP (mmHg) | Diastolic BP (mmHg) |
|---|---|---|
| Elevated | 120-129 | <80 |
| Grade 1 (mild) hypertension | 130-139 | 80-89 |
| Grade 2 (moderate) hypertension | 140-159 | 90-99 |
| Grade 3 (severe) hypertension | ≥160 | ≥100 |
Initial Evaluation of Hypertensive Patients
- Assess for cardiovascular risk factors and comorbidities 2
- Evaluate for target organ damage (left ventricular hypertrophy, retinopathy, chronic kidney disease) 2
- Laboratory tests should include:
- Screen for secondary causes of hypertension when clinically indicated 2
Special Considerations
- Standing blood pressure should be measured in elderly patients and those with diabetes to exclude orthostatic hypotension 1, 2
- In pregnant individuals with diabetes and chronic hypertension, a blood pressure threshold of 140/90 mmHg is recommended for initiation or titration of therapy 1
- For borderline cases, more stringent confirmation with measurements on multiple occasions is recommended 1
Common Pitfalls to Avoid
- Diagnosing hypertension based on a single measurement 2
- Using an inappropriate cuff size (too small overestimates, too large underestimates blood pressure) 2
- Not allowing an adequate rest period before measurement 2
- Talking during blood pressure measurement 2
- Failing to consider white coat or masked hypertension 1, 2
- Not assessing for orthostatic hypotension in elderly or diabetic patients 2
Remember that hypertension is a major risk factor for cardiovascular disease, heart failure, and microvascular complications, making accurate diagnosis essential for appropriate management 1, 3.