Cystatin C W/EGFR test

[Snowpeak]

My husband is nearing dialysis with low kidney function. His Nephrologist added this blood test which is supposed to be the “gold standard” in measuring kidney function. He came in at 9.32 %. Has anyone else had this test?

[Blackknight1989]

The test you mentioned is any “gold standard” but it is the preferred test as this test measures (with an accuracy of about plus and minus of 30%). If your husband had the test today it could vary by as much as 30%. However, it is the most common test used to monitor long-term kidney function to help your Nephrologist know when to recommend the initiation of dialysis.

[Snowpeak in reply to Blackknight1989]

Thank you for your response. My husband has been trying to avoid dialysis but I think his Dr will have him begin very soon.

[Tolmezzo]

There's lot of discussion if Cystatin C is more accurate than Creatinine or others: BUN, clearannce, etc. The real point is that people in so late stage cannot be assessed looking at single value. You need full blood test panel including electrilites 24h urine, emogas and protein electrophoresis. RGS

[Snowpeak in reply to Tolmezzo]

you are right, so many different test to access. However, combined with his symptoms it seems he needs to start dialysis before it becomes an emergency.

[Bassetmommer NKF Ambassador]

This test is just one more diagnostic test that Nephrologist are using. Very similar to GFR it measure components of the filtration of the kidneys. I am surprised your husband is not on dialysis. You should be making steps to do so because whatever process you decide on takes time to put in place. You don't want to go the route of an emergency catheter in the chest if you can help it. The process for getting a fistula takes time and the PD catheter requires surgery and healing as well. Wish you both the best.

kidney.org/atoz/content/cys...

[Snowpeak in reply to Bassetmommer]

Thank you for your advice. My husband already has a mature fistula in place. His symptoms also indicate that he is in need of dialysis. I expect his kidney Dr to set it up this Thursday. My husband is hard headed and been trying his best to hold off but again, it is time to start.

[Bassetmommer NKF Ambassador in reply to Snowpeak]

oh fantastic on the fistula. Too many people do not know you have to let it mature. I too would want to wait as long as possible to start. If he is feeling ok, good for him. I have no symptoms but my GFR is 13 -15. My surgery is scheduled for June.

[Darlenia in reply to Snowpeak]

Glad he took the steps to be ready. My hubby didn't and we paid the price with an emergency hospital stay followed by lots of additional hoopla to then switch to a more permanent solution. Your hubby should have a smooth path to dialysis with everything being handled on an outpatient basis.

[Snowpeak]

Glad you are getting prepared. Best wishes.

[Blackknight1989]

Link on information about eGFR using Cystatin C if still interested: healio.com/news/nephrology/...

[Snowpeak in reply to Blackknight1989]

I found another link that I failed to copy that lists the equation some Drs use to combine the Cystatin C # with the Creatinine # and a few other levels to come up with a seemingly more accurate assessment. I will ask the Dr about this on Thursday. Bottom line is that my husband is clearly nearing beginning dialysis.

Thank you for the above link with information.

[Blackknight1989]

Yes ma’am. Unfortunately there are over 70 tests for eGFR, all different and eGFR can vary from true gfr called mGFR by up to 30%. It’s been my experience that most doctors rely on other tests as the decision to start dialysis bears. I’m not saying your doctor is wrong just letting you know what I’ve read and experienced. My best to you and your husband as you make this decision!

[Futureckd]

Cystatin C is more accurate than creatinine level test when the eGFR is low, my neph adds it to the creatinine in blood test. Sometimes they both give the same eGFR calculation , although there are two different equations, and sometimes they don’t give same calculation of eGFR. So the neph prefers it over creatinine. This is only because my eGFR is low. For high eGFR , creatinine level and equation give more accurate eGFR.

[Marvin8 in reply to Futureckd]

If your thyroid is completely normal, the Cystatin-c + Creatinine formula is nearly as accurate as an actual measured GFR. Again, your thyroid has to be normal or else the Cystatin-c formula is invalid.

[Futureckd in reply to Marvin8]

I never heard that from any nephrologist , even my nephrologist in Mayo Clinic. So I am not sure about the accuracy of what you said. But I will double check this information.

[Marvin8 in reply to Futureckd]

Nephrologists don't like to discuss the intricacies of creatinine, let alone cystatin c. Do the research and you'll see. My serum creatinine and cystatin c eGFR differ by 30 pts. Typically, that means that there's something else going on with either the creatinine or cystatin c. In my case, I suspect some hypothyroidism, which is common with CKD. Hypothyroidism tends to lower the cystatin c levels which in turn artificially raises the eGFR. Hyperthyroidism causes the opposite. It's really quite a conundrum, and it's been difficult getting both my primary and nephrologist to delve deeper into potential thyroid issues than merely running a full thyroid panel. It's much easier for them to simply go by creatinine and leave it at that....because that's what they're trained in.

journals.lww.com/kidney360/...

[Futureckd]

I met my Mayo Clinic nephrologist and he confirmed that Cystatin c in blood test id more accurate than creatinine when egfr is low. He said that Creatinine level can be affected by dehydration , food eaten before the test, and other factors that don’t affect Cystatin c . So Cystatin c is more accurate. Everyone can decide for himself /herself and discuss with one’s nephrologist. This is just my own case.

[Snowpeak in reply to Futureckd]

my husband met with his neurologist yesterday and because his Cystatin C levels were so low (9.32) with his accompanying symptoms, he wants him to start dialysis. My husband said, not yet. Next appointment is 2 months. Will see how this all goes. Thanks for asking your Dr.