Pathophysiology
P-I-19. Diagnostic criteria of hypertension by measurement method
各測定法による高血圧の診断基準；家庭血圧測定
Diagnostic Criteria of Hypertension
- Office hypertension: the average of the last two of three measurements is >140/90 mmHg, taken at the medical office, with the patient at rest, on ≥ three occasions about one week apart
- The cut-off differs by measurement method — out-of-office methods use lower thresholds because readings are typically lower than in the office
Thresholds by Measurement Method
| Method | Systolic (mmHg) | Diastolic (mmHg) |
|---|---|---|
| Medical office | ≥140 | ≥90 |
| Home | ≥135 | ≥85 |
| ABPM — daytime | ≥135 | ≥85 |
| ABPM — nighttime | ≥120 | ≥70 |
| ABPM — 24-hour | ≥130 | ≥80 |
Home Blood Pressure Monitoring
Indications
- White-coat hypertension — BP rises at the doctor’s office but is lower when measured at home
- Recommended especially in pregnant, elderly and diabetic patients, and in those with suspected white-coat hypertension
Benefits
- Uses a lower cut-off (135/85 mmHg) appropriate to the home setting
- Provides multiple real-life readings outside the clinical environment
- Helps distinguish white-coat and masked hypertension, improving diagnostic accuracy and treatment decisions
一問一答
▶How is office hypertension formally defined?
The average of the last two of three measurements is >140/90 mmHg, taken at rest in the office on ≥3 occasions about a week apart.
▶Why do out-of-office BP methods use lower diagnostic thresholds?
Because readings outside the office are typically lower than in-office readings.
▶What is the office (medical-setting) hypertension threshold?
Systolic ≥140 mmHg or diastolic ≥90 mmHg.
▶What is the home BP hypertension threshold?
Systolic ≥135 mmHg or diastolic ≥85 mmHg.
▶What are the ABPM daytime, nighttime, and 24-hour hypertension thresholds?
Daytime ≥135/85, nighttime ≥120/70, 24-hour ≥130/80 mmHg.
▶What is the main indication for home blood pressure monitoring?
Suspected white-coat hypertension — BP rises at the doctor's office but is lower when measured at home.
▶In which patient groups is home BP monitoring especially recommended?
Pregnant, elderly, and diabetic patients, and those with suspected white-coat hypertension.
▶What cut-off does home BP monitoring use?
A lower cut-off of 135/85 mmHg, appropriate to the home setting.
▶What are the main benefits of home blood pressure monitoring?
Provides multiple real-life readings outside the clinic and helps distinguish white-coat and masked hypertension, improving diagnostic accuracy and treatment decisions.
▶How many occasions and readings are needed to diagnose office hypertension?
At least three occasions (about a week apart), each with three measurements, averaging the last two.
▶Why is averaging the last two of three readings used rather than the first?
The first reading is often the highest (alerting reaction); later readings better reflect true resting BP.
▶How does home monitoring help distinguish masked hypertension?
It reveals elevated BP outside the clinic that would be missed by normal office readings.
▶Why is the patient required to be at rest for office BP diagnosis?
Rest minimizes transient sympathetic elevation, giving a more accurate baseline reading.
▶Why is multiple-occasion measurement (over weeks) required before diagnosing hypertension?
BP varies day to day; repeated measurements confirm sustained elevation rather than a transient spike.
▶Why is home BP monitoring especially valuable in diabetic patients?
Diabetics have high cardiovascular risk and may have masked hypertension; home monitoring improves detection and guides tighter control.
▶Why is BP measured on both arms initially?
To detect inter-arm differences; the higher arm is used for subsequent measurements, and large differences suggest vascular disease.
▶How do home and ABPM-daytime thresholds compare?
They are the same: ≥135/85 mmHg.
▶Which method gives the lowest diagnostic threshold for hypertension?
ABPM nighttime (asleep), at ≥120/70 mmHg.
▶How does out-of-office monitoring improve treatment decisions?
By confirming true hypertension and avoiding unnecessary treatment of white-coat hypertension, it tailors therapy more accurately.
▶Why is home monitoring recommended in pregnancy?
It allows frequent BP surveillance to detect gestational hypertension/pre-eclampsia while avoiding white-coat overdiagnosis.