The Link Between Blood Pressure Medication and Kidney Damage

 by Muhammed Sahil

Recently, research from the University of Virginia School of medicine found that the long term use of medication used to treat hypertension (high blood pressure) and heart failure may be a contributing factor to kidney damage.

Hypertension affects more than 1 billion people worldwide and is a risk factor of cardiovascular disease. Currently many types of medicine are available to help control hypertension including ACE inhibitors, angiotensin-2 receptor blocker (ARB) or calcium channel blockers.

ACE inhibitors reduce blood pressure through causing the relaxation of your blood vessels. They work by preventing an enzyme in the body from producing angiotensin II, a substance that narrows blood vessels and produces hormones that raise blood pressure.

ARBs function similarly to ACE inhibitors and are often used by patients who had side effects to ACE inhibitors. 

Calcium channel blockers work by causing vasodilation of blood vessels, thus reducing blood pressure. They do this by preventing calcium from entering the cells of the heart and arteries. Calcium causes the blood vessels to contract forcefully, thus reducing the size of the lumen, meaning the rate of blood flow is significantly reduced. 

Diuretics can also be used. Normally, your kidneys filter out water, salts and waste from the blood. Most of the water contains salt which is then taken up by the bloodstream but some is left in urine. Diuretics are a type of pill which prevent salts and water from being taken back into the blood. They flush excess water and salt from the body through your urine. The sodium also helps to remove water from the blood, meaning less fluid flows through the veins and arteries. The reduced volume of the blood helps to lower blood pressure.

Beta blockers make your heart beat more steadily and with less force. However since they’re less effective, this form of treatment is quite uncommon and only used when other forms of treatments don’t work. They specifically work by blocking the effects of the hormone epinephrine (more commonly known as adrenaline) as these hormones can’t bind to the heart’s beta receptors.

What causes Kidney damage?

Scientists have found that renin cells which are a type of kidney cell play an important role in the regulation of blood pressure by secreting a hormone called renin. If changes occur to these cells, they could end up invading the walls of the kidney’s blood vessels. The renin cells trigger smooth muscle cells to build up in blood vessels, which causes the walls to thicken so blood flow to the kidneys is reduced and less efficient.

In terms of medication, research has found that ACE inhibitors or angiotensin receptor blockers have a similar effect. Though these drugs are used to treat hypertension, congestive heart failure and heart attacks, long term use of these drugs can cause the hardening of kidney blood vessels, following lab studies on mice and humans. 

Despite the potential harmful effects, patients should continue taking the lifesaving drugs prescribed by their doctors. Without medication, high blood pressure will increase the risk of damage to your artery walls, which then leads to an increased risk of atheromas forming. An atheroma is a fibrous plaque which partially blocks the lumen of the artery and thus restricts blood flow. This can cause a further increase in blood pressure and can lead to blood clots, which block the flow of blood to the heart muscles. This can result in a myocardial infarction (heart attack). Therefore it’s vital to realise that the overall benefits of these drugs are much greater than the potential risks. In addition more research is required to fully understand the long term effect these drugs have on the kidneys.