Blood pressure measurement is of fundamental importance – always remembering that measurements at different times can produce quite different results, depending on the patient’s general state. Repeated blood pressure measurements on different days, and ideally at different times of day, are therefore necessary for a firm diagnosis of hypertension. The patient should be allowed to rest briefly before having blood pressure measured in the seated position in both upper arms. Ambulatory 24-hour blood pressure measurements or self-measurements, with values recorded together with the exact time of measurement, increase the certainty of the diagnosis.

During the consultation the doctor clarifies the following points:

• Cases of hypertension or heart disease in the family?
• Previous blood pressure readings?
• Any known pre-existing diseases (coronary artery disease, kidney disease, diabetes, etc)?
• Does the patient regularly take any medicines?
• Is he/she overweight?
• What does he/she eat?
• Does the patient smoke or consume alcohol, coffee or other natural stimulants in large amounts?
• Is there constant stress?
• For women: Did their blood pressure increase  when they were pregnant?

During the physical examination, the doctor listens to the heart, neck and lungs and examines the kidneys and back (fundus) of the eye. Of particular interest are any differences in pulse or blood pressure between the right and left arms or legs, because they could indicate peripheral vascular disease.

Other investigations are laboratory tests and urinalysis, ECG and exercise ECG, and echocardiography (ultrasound of the heart).
Classifications of hypertension

The normal values advocated by the World Health Organisation (WHO) and the German medical associations are:

Category	Systolic (mmHg)	Diastolic (mmHg)
Optimal blood pressure	<120	<80
Normal blood pressure	120–129	80–84
High normal blood pressure	130–139	85–89
Mild hypertension (grade 1)	140–159	90–99
Moderate hypertension (grade 2)	160–179	100–109
Severe hypertension (grade 3)	>180	>110
Isolated systolic hypertension	>140	<90

The guidelines published in the USA (JNC7 report) differ only slightly from this; for example, they do not define an additional grade 3.