Angiotensin receptor blockers (ARBs) are medications used to lower blood pressure.
In Alport syndrome patients, genes that provide instructions to build a structural protein called type 4 collagen are mutated. Type 4 collagen is part of the glomerular basement membrane in the kidneys, which plays an essential role in filtering blood.
The kidneys also control blood pressure by regulating the electrolyte or salt concentrations in the blood. Alport syndrome patients frequently have high blood pressure, which is likely caused by defects in kidney function. High blood pressure further damages the kidney, leading to proteinuria (the presence of protein in the urine).
ARBs may be used to lower blood pressure in Alport syndrome patients. They can be taken in combination with angiotensin-converting-enzyme (ACE) inhibitors. ARBs are also used as an alternative to ACE inhibitors in patients who cannot tolerate these medications.
How ARBs work
ARBs interfere with the activity of angiotensin 2, a hormone that causes an increase in the production of two other hormones, vasopressin and aldosterone.
Vasopressin causes blood vessels to narrow, and aldosterone is involved in the retention of sodium and chloride. High salt concentrations in the blood lead to an increase in blood volume.
In combination with the narrowing of the blood vessels, this leads to a rise in blood pressure. ARBs work by blocking the receptors to which angiotensin normally binds. As a result, blood pressure decreases.
ARBs for Alport syndrome
ARBs are usually well-tolerated, and most people do not experience side effects. Possible side effects are dizziness, elevated potassium levels, and localized swelling of tissues.
Because ARBs lead to an increase of potassium levels, individuals taking these medications should try to limit their potassium intake by not eating too many dairy products, nuts, salt substitutes, and certain fruits and vegetables.
When used in combination with ACE inhibitors, ARBs can cause low blood pressure.
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