Secondary hypertention is abnormally high blood pressure caused by pre-existing clinical conditions.
Some causes of secondary hypertention are listed below:
o Nephron function impaired
o Blood volume and BP increases
o May evoke more damage and kidney failure
Renal artery stenosis
o Narrowing of renal artery, this induces high blood pressure
o Renin production and BP increases
The stenosis stimulates renin release by the kidney, which increases circulating angiotensin II (AII) and aldosterone. These hormones increase blood volume by increasing kidney reabsorption of sodium and water. Increased AII also causes systemic vasoconstriction increasing blood pressure. The figure below shows the action of the renin release by the kidney.
o Aldosterone ↑ Na+ BP ↑
o High oestrogen (pill) ↑ liver angiotensinogen
This is a condition that can be seen in pregnancy that causes hypertension due to increased blood volume and tachycardia.
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