Dr Kola Tytler MBBS CertHE MBA MRCGPClinical Lead • iatroX
According to UK guidelines, the diagnosis of hypertension in adults is confirmed when a person has a clinic blood pressure of 140/90 mmHg or higher, alongside an ambulatory blood pressure monitoring (ABPM) daytime average or home blood pressure monitoring (HBPM) average of 135/85 mmHg or higher NICE NG136.
The diagnostic process typically involves several steps:
- Initial Clinic Measurement: When considering a diagnosis, blood pressure should be measured in both arms NICE NG136. If the clinic blood pressure is 140/90 mmHg or higher, a second measurement should be taken during the same consultation NICE NG136. If the second measurement is substantially different from the first, a third measurement should be taken, and the lower of the last two measurements recorded as the clinic blood pressure NICE NG136.
- Confirmatory Monitoring: If the clinic blood pressure is between 140/90 mmHg and 180/120 mmHg, ABPM should be offered to confirm the diagnosis NICE NG136. If ABPM is unsuitable or the person is unable to tolerate it, HBPM should be offered instead NICE NG136.
- ABPM Protocol: For ABPM, at least two measurements per hour should be taken during the person's usual waking hours (for example, between 08:00 and 22:00) NICE NG136. The average value of at least 14 measurements taken during waking hours is used to confirm the diagnosis NICE NG136.
- HBPM Protocol: For HBPM, two consecutive measurements should be taken at least one minute apart with the person seated for each recording NICE NG136. Blood pressure should be recorded twice daily, ideally in the morning and evening, for at least four days, and ideally for seven days NICE NG136. Measurements from the first day should be discarded, and the average of all remaining measurements used for diagnosis NICE NG136.
- Further Actions: While waiting for diagnosis confirmation, investigations for target organ damage and a formal assessment of cardiovascular risk should be carried out NICE NG136. If hypertension is not diagnosed, clinic blood pressure should be measured at least every five years subsequently, and considered more frequently if the person's clinic blood pressure is close to 140/90 mmHg NICE NG136.