Classifications of Hypertension

Hypertension is divided into primary hypertension where there is no identifiable cause and secondary hypertension where a cause can be determined.
The following classification of raised blood pressure is taken from The Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood pressure (JNC VI). It defines the grades of blood pressure according to its severity. It is based on blood pressure for adults aged 18 and older who are not on treatment for high blood pressure.

Category	Systolic (mm Hg)		Diastolic (mm Hg)
Optimal	<120	and	<80
Normal	<130	and	<85
High normal	130-139	Or	85-89
Hypertension
Stage 1	140-159	Or	90-99
Stage 2	160-179	Or	100-109
Stage 3	>=180	Or	>=110