This week was the start of a new physiology block with an amazing professor. His clear-headed view of health and wellness is so inspiring. He calls it his “soapbox” but I often get on the same soapbox, so to me, he is preaching to the choir (something that doesn’t happen as often as I’d like). What is this soapbox you ask? Since you had to ask, I’ll get on mine for a bit now. America is a nation of excess. Supersize this and extra butter on that, followed with “gotta have it” ice cream and apple pie that has more sugar than apples. People want it all but don’t want to deal with the consequences. Instead, they want medical professionals to make those consequences go away – NOW – and with a pill, if possible. Ohh, or even better…with a herbal supplement; since it is natural, it must be better. But anyway, I’ll leave it there for now…
So how does this tie into the kidneys and NSAIDs? It’s coming! In class we are talking renal physiology and Dr. Strang raised an interesting concern. Prostaglandins are little compounds formed by the body when it is under stress. They help with the immune response and make sure that blood gets to where it needs to go. In the kidney, they vasodilate the blood vessel (make it bigger) so that blood continues to flow to the kidney, even when the body is stressed. This is important, because if blood flow drops, the kidney’s functional units (aka nephrons) will die and the kidney won’t work well any more. A short-term problem is called AKI (acute kidney injury) and a long-term problem, which is irreversible, is called CKD (chronic kidney disease). So what does this have to do with NSAIDs? Well, NSAIDs are the over-the-counter pain killers we use every day. How do they work? They block the production of prostaglandins. Starting to see the picture? So, excessive use alone can decrease blood flow to the kidney by blocking the normal vasodilation.
But you may be thinking, “Oh, I only use it once and a while, like when I’m sick or had a little too much to drink.” Actually, these are times when you need to be the most careful. If you are dehydrated, your kidneys are wanting to vasoconstrict the blood vessels because there is less fluid in your blood; they want to maintain the pressure…think of water flowing through a hose – if you turn it down the pressure drops. If you put your finger on the end and make the opening smaller the pressure will rise again. Prostaglandins help prevent this compensation, because we don’t want blood flow to your kidney to fall (remember those nephrons!). If you take a few NSAIDs because you have a headache (likely related to the dehydration), you will prevent these guys from doing their job. You will decrease the blood flow, which is already decreased due to dehydration. The example Dr. Strang gave in class was a 20-something college student who took a few extra NSAIDs after a night of drinking and woke up to an AKI.
The largest problem comes in when people don’t read the labels, or think that over the counter means it is safe to take as much as you’d like. While shadowing in urgent care I saw a lady who was taking 2-3X the max dose of Alieve daily for weeks. She was lucky to not be in kidney failure at that point. She assumed that since it was over the counter she could double or triple the dose.
NSAIDs have their purpose – I don’t want to scare you out of taking them. Just remember to always follow the directions on the label and drink LOTS of water. Even better…try to figure out why you have the headache in the first place you can prevent it from happening next time.