primary hypertension

Last reviewed 05/2021

Primary or essential hypertension refers to hypertension without demonstrable cause. It accounts for 95% of all cases of hypertension and is a diagnosis of exclusion.

Blood pressure is normally distributed in the population and there is no natural cut-off point above which 'hypertension' definitively exists and below which it does not

  • risk associated with increasing blood pressure is continuous, with each 2 mmHg rise in systolic blood pressure associated with a 7% increased risk of mortality from ischaemic heart disease and a 10% increased risk of mortality from stroke
  • diastolic pressure is more commonly elevated in people younger than 50. With ageing, systolic hypertension becomes a more significant problem, as a result of progressive stiffening and loss of compliance of larger arteries
  • at least one quarter of adults (and more than half of those older than 60) have high blood pressure.

NICE have classified hypertension as:

This guidance uses ambulatory or home monitoring to confirm stage 1 or stage 2 hypertension.

Stage 1 hypertension

  • clinic blood pressure is 140/90 mmHg or higher AND
    • subsequently Ambulatory blood pressure monitoring (ABPM) daytime average OR Home blood pressure monitoring (HBPM) average blood pressure is 135/85 mmHg or higher.

Stage 2 hypertension

  • clinic blood pressure is 160/100 mmHg or higher AND
    • subsequently ABPM daytime average or HBPM average blood pressure is 150/95 mmHg higher.

Severe hypertension

  • clinic systolic blood pressure is 180 mmHg or higher or clinic diastolic blood pressure is 110 mmHg or higher


  • the diagnosis of hypertension should not be made on the basis of a single elevated reading. In many cases, a second blood pressure reading is lower, and often, a third lower still
  • patients found to have malignant or accelerated phase hypertension should be referred to hospital as an emergency
  • the majority of patients will have essential hypertension but it is nevertheless imperative to fully investigate for secondary causes
  • assessment should also consider other risk factors for cardiovascular disease and stroke


  1. NICE (November 2016). Clinical management of primary hypertension in adults