Poor kidney function

[MommyJuneandJo]

Mom has been diagnosed with pmr since April of this year and was on 40mg, now she's on 7mg and doing really well. However, her kidney function seems to be affected, not sure if it's her age, she's 81, but her recent blood test showed they are only functioning at 34%, and her GP is now referring her to a consultant nephrologist for further investigation. Unsure if it's her other medication which she takes which are statins and blood pressure but at one point this year her blood test revealed 90% kidney function. Any feedback would be helpful.

[DorsetLady PMRGCAuk volunteer]

hi,

sorry to hear that, but it's probably of combination of tablets and age. Certainly some blood pressure tablets can affect the kidney function, likewise with Pred (what doesn't it affect?) plus as we get older everything becomes less efficient. Mine was under review when on higher doses of Pred, but fortunately it seems to have stabilised now, but I am 12 years younger than your Mom.

Hopefully the consultant will be able to come up with something that will reverse her downward function.

[PMRpro Ambassador]

I doubt it is the pred - it is used to improve renal function in some cases and high dose pred increases GFR. However, statins are being linked with kidney problems, especially when used at high doses.

The other thing that should perhaps be considered is whether she has autoimmune renal damage - having one autoimmune disorder makes it more likely you will develop another.

I have to say - I am rather sceptical about a lady of 81 having an eGFR of 90! The glomerular filtration rate falls as we age anyway. Was that result after she started pred? If so, it may have been artificially high because high dose steroids do increase the result in the first few weeks. In the case of the most recent - had she been drinking plenty? Dehydration can reduce the eGFR result and we all know, elderly people don't like drinking too much so they don't have to make the journey to the bathroom so often. So it is possible that the first was high, the second low - and the truth is somewhere in between.

Extra bit of investigation brings this (which I knew but had forgotten): "eGFR may not be as useful for those who differ from normal creatinine concentrations. This may include people who have significantly more muscle (such as a body builder) or less muscle (such as a muscle-wasting disease) than the norm, those who are extremely obese, malnourished, follow a strict vegetarian diet, ingest little protein, or who take creatine dietary supplements. Likewise, the eGFR equations are not valid for those who are 75 year of age or older because muscle mass normally decreases with age."

Your mum's muscle mass has almost certainly fallen while she has had PMR (both lack of exercise and use of corticosteroids) - so the eGFR may not be an accurate measure. I'm assuming your GP didn't measure it properly with a 24 hour urine collection and a blood test taken during the collection? These are just the figures that come from the lab with any blood test that includes creatinine?

Do let us know how she gets on. But in the meantime, don't worry too much, she is still a long way from renal failure.