Hypertension

Hypertension is the term used to describe high blood pressure. The NICE guidelines on hypertension from 2019 suggest a diagnosis of hypertension with a blood pressure above 140/90 in clinic or 135/85 with ambulatory or home readings.

 

Causes of Hypertension

Essential hypertension accounts for 95% of hypertension. This is also known as primary hypertension. It essentially means that the hypertension has developed on its own and does not have a secondary cause.

There are secondary causes of hypertension that you can remember with the mnemonic ROPE:

  • RRenal disease. This is the most common cause of secondary hypertension. If the blood pressure is very high or does not respond to treatment consider renal artery stenosis.
  • OObesity
  • PPregnancy induced hypertension / pre-eclampsia
  • EEndocrine. Most endocrine conditions can cause hypertension but primarily consider hyperaldosteronism (“Conns syndrome”) as this may represent 2.5% of new hypertension. A simple test for this is a renin:aldosterone ratio blood test.

Specialist investigations should be considered in patients with a potential secondary cause for their hypertension or aged under 40 years.

 

Complications

  • Ischaemic heart disease
  • Cerebrovascular accident (i.e. stroke or haemorrhage)
  • Hypertensive retinopathy
  • Hypertensive nephropathy
  • Heart failure

 

Diagnosis

NICE recommend measuring blood pressure every 5 years to screen for hypertension. It should be measured more often in patients that are on the borderline for diagnosis (140/90) and every year in patients with type 2 diabetes.

Patients with a clinic blood pressure between 140/90 mmHg and 180/120 mmHg should have 24 hour ambulatory blood pressure or home readings to confirm the diagnosis. Having your blood pressure taken by a doctor or nurse often results in a higher reading. This is commonly called “white coat syndrome”. The white coat effect is defined as more than a 20/10 mmHg difference in blood pressure between clinic and ambulatory or home readings.

NICE recommend measuring blood pressure in both arms, and if the difference is more than 15 mmHg using the reading from the arm with the higher pressure.

 

Stages

Stage

Clinic Reading

Ambulatory / Home Readings

Stage 1 Hypertension

>140/90

>135/85

Stage 2 Hypertension

>160/100

>150/95

Stage 3 Hypertension

>180/120

 

End Organ Damage

NICE recommend all patients with a new diagnosis should have:

  • Urine albumin:creatinine ratio for proteinuria and dipstick for microscopic haematuria to assess for kidney damage
  • Bloods for HbA1c, renal function and lipids
  • Fundus examination for hypertensive retinopathy
  • ECG for cardiac abnormalities

 

Medications

  • A – ACE inhibitor (e.g. ramipril 1.25mg up to 10mg once daily)
  • B Beta blocker (e.g. bisoprolol 5mg up to 20mg once daily)
  • C – Calcium channel blocker (e.g. amlodipine 5mg up to 10mg once daily)
  • D – Thiazide-like diuretic (e.g. indapamide 2.5mg once daily)
  • ARB – Angiotensin II receptor blocker (e.g. candesartan 8mg to up 32mg once daily)

Angiotensin receptor blockers are used in place of an ACE inhibitor if the person does not tolerate ACE inhibitors (commonly due to a dry cough) or the patient is black of African or African-Caribbean descent. ACE inhibitors and ARBs are not used together.

 

Initial Management

Establish a diagnosis.

Investigate for possible causes and end organ damage.

Advise on lifestyle. This includes recommending a healthy diet, stopping smoking, reducing alcohol, caffeine and salt intake and taking regular exercise.

 

Medical Management

Medical management is offered to: a

  • All patients with stage 2 hypertension
  • All patients under 80 years old with stage 1 hypertension that also have a Q-risk score of 10% or more, diabetes, renal disease, cardiovascular disease or end organ damage.

There are slightly different guidelines for younger patients and those aged over 55 or black:

  • Step 1: Aged less than 55 and non-black use A. Aged over 55 or black of African or African-Caribbean descent use C.
  • Step 2: A + C. Alternatively A + D or C + D. If black then use an ARB instead of A.
  • Step 3A + C + D
  • Step 4A + C + D + additional (see below)

For step 4, if the serum potassium is less than or equal to 4.5 mmol/l consider a potassium sparing diuretic such as spironolactone. If the serum potassium is more than 4.5 mmol/l consider an alpha blocker (e.g. doxazosin) or a beta blocker (e.g. atenolol).

Seek specialist advice if the blood pressure remains uncontrolled despite treatment at step 4.

 

Potassium Balance

Spironolactone is a “potassium-sparing diuretic” that works by blocking the action of aldosterone in the kidneys, resulting in sodium excretion and potassium reabsorption. This can be helpful when thiazide diuretics are causing hypokalaemia.

Using spironolactone increases the risk of hyperkalaemia. ACE inhibitors can also cause hyperkalaemia. Thiazide like diuretics can cause also electrolyte disturbances. For this reason it is important to monitor U+Es regularly when using ACE inhibitors and all diuretics.

 

Treatment Targets

Age

Systolic Target

Diastolic Target

< 80 years

< 140

< 90

> 80 years

< 150

< 90

 

Last updated March 2020
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