24 hr Calcium Urine Test

[Chris_1236]

I would be interested in knowing what results others have received on this test since being on Pred.

I know Pred leaches Ca from the bones. That Ca goes somewhere and if it's not hanging out in the blood, then most likely it's being dumped by the kidneys. Or so it seems to me. It could be plaquing up somewhere, but at 3L of water a day and <500mg/day Ca intake, probably not.

My results for this test tend to run 320-350 mg/24 hr. The high end of LabCorp's scale is 320.

My Ca and Ionized serum Ca are mid to upper range where expected.

My thoughts are that the elevated urine level is due to Pred. But maybe not. Hence this post of inquiry as to what results others have seen.

My last dexa (2yrs ago) was perfect. I have another scheduled later this month.

Fwiw, eGFR is fine averaging 91. I'll have an mGFR next round of labs.

Chris

[PMRpro Ambassador]

It isn't just that - and the main action is to reduce the absorption of calcium in the gut. It has been shown that increasing the amount of calcium ingested, using supplements if necessary, maintains the amount absorbed. That will increase the amount of calcium in the urine, and is why some people develop cystitis because grit forms in the urine.

"Steroids cause bone loss by a variety of mechanisms. They act to decrease absorption of calcium from the intestine, and increase urinary calcium loss. This leads to the development of secondary hyperparathyroidism, which results in bone resorption. Steroids may also directly inhibit osteoblasts from laying down new bone. Male rheumatoid arthritis patients on steroids have been shown to have lower testosterone levels, presumably on the basis of suppressed hypothalmic‐pituitary‐testicular axis."

ncbi.nlm.nih.gov/pmc/articl....

24 hour urine Ca++ estimations aren't a common test in the UK so I doubt you will get much response.

[Chris_1236 in reply to PMRpro]

"Steroids cause bone loss by a variety of mechanisms. They act to decrease absorption of calcium from the intestine, and increase urinary calcium loss."

That last phrase probably explains it.

Interesting bit about testosterone as well. I was not aware of that.

That link is helpful, thank you!

Hope folks have a great weekend. The weather is beautiful in NC today.

[Chris_1236 in reply to Chris_1236]

One further observation:

I just realized that I did the urine collection the last day of the Pred spike for my disc issue. So my kidneys might have been working overtime at that point in time.

[Sophiestree]

Did you have the 24hr urine test to check for anything? I only ask as pre diagnosis my calcium levels were quite high and I was told to drink 3 litres a day (which was far harder than I thought) and this test was something I was about to have. I ended up having a parathyroid gland removed as it had a large (which the surgeon told me after) benign tumour on it. My calcium dropped down to normal levels after this.I should also say that once I started pred the calcium dropped but as I reduced they started to rise again along with the PTH and so they brought the surgery forward then.

[Chris_1236 in reply to Sophiestree]

Since having been hospitalized in 2020 for C19, I have been on a high dose of D3 under the supervision of my GP. I have lab work done quarterly and this particular check is to watch for hypercalciuria and to be sure my kidneys are not being stressed.

This is the first time it has been above the upper limit of the lab range. Since I maintain a very strict diet I was curious as to what might factor in to the cause. Of course it could just be anonymous. So I'll probably request another test in a few weeks just to be sure we're not missing anything.

BTW, Chronometer is an excellent app for tracking micronutrients if you are into that sort of thing.

Disclaimer: This is not intended to be medical advice of any sort.

Chris