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Comment by ai_fry_ur_brain | Hacker News Reader

This is a myth, its not bad for your kidneys. The reason this gets spread is because you will have higher levels of creatine in your urine if your Doctor tests your urine for kidney function, which indicates kidney disease.

However, If you reveal to that doctor that you're supplementing Creatine it will not be concern them.

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My dad's GP didn't know about this, and despite my dad saying "it's fine, I'm taking creatine", sent him for a kidney check-up. Then they found an unrelated tumor on the ultrasound. Seems to be benign and hopefully all will be well. If so, creatine saved his life ;)

> creatine saved his life

Or more correctly, the myth saved his life.

Perhaps sometimes we should listen to conspiracy theorists. /s

I've even had doctors unaware that the regular eGFR tests needs to be adjusted for body mass to be remotely accurate if you're bigger than average - e.g. lifting weights or obese. Couple that with creatine and you get some "fun" moments when your doctor tries to gently break to you how messed up they think your kidneys are. The first time I had that I'd warned my doctor ahead of time to expect elevated creatinine, and he still freaked out.

Creatinine not Creatine

This has been my understand as well. I have CKD and my doctors have always been chill about it as long as I stop taking it about a week before having blood work done.

EDIT: I don't do 25g though... sounds like a lot...

You're lucky your doctor is aware of it. I've had several who did not understand, and insisted creatine must be dangerous if it elevated creatinine levels, and/or didn't understand the effects.

If your egfr is above 80 it’s you won’t notice it. But CKD is a late in life problem so you are basically making your end of life worse by making your kidneys work harder now. You might as well take up smoking: claiming it doesn’t hurt now is a lot different to 20 years of constant use.

At the risk of sounding stupid. Doesn’t this mean it would mask actual kidney disease? So you’d be ignoring potential warning signs.

IF you tell your doc, they can adjust their interpretation of the test.

Edit: see comment below (i.e. better to stop taking creatine at least a week before a test).

There is a much more accurate test called Cystatin C that can be used instead, and it isn't subject to being thrown off by creatine, muscle mass, etc.

If you have a good dr they'll just ask you to stop taking it for two weeks, then do a blood test.

creatinine != creatine

It's pretty clear they understand that. Creatinine is, however, the waste product of creatine. So the more creatine you consume, the more creatinine is in and discharged from your system.

Precisely and correctly as they said, normal eGFR presumes average musculature and average creatine consumption. If either of these out of the norm, eGFR becomes inaccurate and potentially flagging false positives for damage. Creatinine, the waste product of creatine, raises in a way that can get confused with kidney damage, which is precisely how the confusion about it causing kidney damage or being bad if you have a compromised kidney came about.

In some studies, people with CKD actually improved with creatine supplementation, though notably this was not people with PKD where it could increase cyst growth.

I started taking creatine after trying to clarify which one of those was which and found the dearth of negative consequences

Careful.

Creatine metabolizes into creatinine which is major indicator of kidney function because not being able to clear creatinine means your kidneys aren’t working. Adding more creatinine to your system decreases your ability to clear it leading to fatigue, edema, high blood pressure etc.

So it isn’t bad for your kidneys: it is bad for everything else.

Except many many many decades of research has not shown any of that to be true.

Creatinine can be an indicator that your kidneys are not working well. It's a cheap red flag that can be screened for in a common blood test. But if heightened creatinine is a result of one's creatine supplementation, then there are none of the downsides associated with kidney disease.

Creatinine itself doesn't cause fatigue, edema, or high blood pressure. Kidney disease does.

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