24 hr Urine Test

[Cbailey]

Hello, I was wondering if anyone has experienced very different GRR's doing a 24 hr urine vs the blood test. I have had stage 3 kidney disease for the last 6 years with a steady decline. I did a 24 hr urine and it showed my GFR to be a 66. The blood test showed a GFR of 31. My GFR has been reading in the 30's for a year now. My doctor said that he believes that my function is better than the30's, and that since Im non-diabetic sometimes the 24 hr urine is a better test. Has anyone seen a difference of 30 points between their tests?

[bumblebee_tuna]

Hmm, I don't remember seeing such a big difference - mine mostly matched. But the 24h urine tests is the gold standard for kidney function so I think this is good news!

[Tolmezzo]

There's a logic in what your doctor said. Blood test is snapshot in one moment, 24h entire day consequently much more representative. So I would always trust more 24h. Rgs

[userotc]

Maybe the link below explains your specific situation (muscle mass changes)? Ideally a doctor would explain his/her reasoning for the differences but sadly few do.

niddk.nih.gov/health-inform....

Does he/she now consider you to be stage 2 with an eGFR of 66? kidneyfund.org/kidney-disea... although consistent trends are better than spot readings.

Either way, the trend of results is more important i.e. increasing or decreasing, whichever test method used, but will the doc continue with 24h for your future function tests?. For info/ref, my mum's last 3 urine 24h protein increased (max 0.44g) in line with (blood) eGFR with the latter being the one tested most so used for kidney function trend.

[Jayhawker]

My nephrologist considers the 24 hour urine sample to be more accurate. However, the data you shared seems like a a very large variance between the 2 types of data. I’d definitely talk with the nephrologist about this.

Jayhawker

[Darlenia]

I "think" you're referring to the uACR (urine) and eGFR (blood) tests. It's kinda complicated in my view. As kidneys fail, the uACR numbers go higher and the eGFR numbers go lower. The urine tests checks for two types of protein (one of the two ideally shouldn't really be there and if it is, it "may" signal diabetes etc.). Ideal numbers for uACR should be 30 or below. The eGFR blood test also looks for protein waste circulating within the body and ideal number should be 60 or above. I tend to agree with your doctor that, since you don't have diabetes, that the urine test may be more accurate. The eGFR test is an "estimate" only with extra variables, like age categories, thrown in which also clouds the picture somewhat in my opinion.

I noticed that as my hubby's kidney started failing and struggled to produce urine, that more and more blood tests were ordered and BUN and Creatinine figures were of intense interest. Post transplant, he now regularly provides blood and urine samples. My hubby is a diagnosed diabetic and also has a chronic uti (which also sheds protein into his urine) and both of these situations really impact his labs. I hope this hasn't confused you. I know it was all very confusing to me for a while. If you're interested, the NKF has a wonderful explanation re uACR and eGFR. I think your doctor is seeing things in the right way. kidney.org/atoz/content/kno....