BETA - How is kidney function monitored and managed?

What do the kidneys do? The kidneys are very important in multiple myeloma. Let's start from the basics. Plasma cells secrete a lot of proteins that has to be cleared out of the blood through the kidneys. Where do those proteins go? They go through the urine. The normal function of the kidneys is to eliminate waste products, excess water, or any toxic metabolites that are produced from whatever we eat or ingest or inhale. And it's the kidney that kind of eliminates it from your body. And so when your kidneys are not working right, you may accumulate more than necessary water or fluid in your body. What are signs of kidney dysfunction? Probably signs of kidney dysfunction may include leg swelling or facial puffiness. Having puffy eyes or swollen eyes and legs would be probably the earliest signs of kidney dysfunction. Feeling nauseous, not having a good appetite, feeling tired or weak, these could be some other signs too. The signs and symptoms of the high kidney enzymes are oftentimes quite nonspecific and they might be related to fatigue or nausea, occasionally vomiting, metallic taste in the mouth. Sometimes patients feel that they are more short of breath or they are bloated or more swollen just because they have a decreased urinary output. Oftentimes they might kind of feel, when they wake up in the morning and they feel not refreshed through the night. Sometimes patients don't even point to any of those symptoms and they come to the clinic with just explaining something, well, something is odd, just not making sense to me. I feel like my urine turned foamy or bubbly and you check their blood levels and you see a comprehensive metabolic panel shows a creatinine of five or six and you might feel like, well, you should usually see more symptoms than you actually are feeling. Are there specific myeloma treatments that may be likely to cause kidney dysfunction? So controlling high blood pressure, controlling diabetes is as important as controlling multiple myeloma, especially in multiple myeloma patients where we give large doses of dexamethasone and that tend to make diabetes worse and therefore kidneys could get injured from there. Which regimens of multiple myeloma affect the kidneys? I have to say that most of multiple myeloma treatments are dose adjusted based on the kidney function. They are not supposed to directly cause kidney damage. There's only one drug, carfilzomib, might cause kidney injury. Usually it's reversible and usually once we start seeing it going up and we believe it's from carfilzomib, we either adjust the dose or stop the drug completely. Multiple myeloma patients can also get kidney damage if they got infections. Example, let's say a patient got melphalan and stem cell transplant while melphalan by itself will not affect the kidney function. If they ended up with an infection and their blood pressure went down or become dehydrated, we will see kidney damage. Talking of which, hydration is very important for the kidneys. Word of caution, those who have kidney damage already, drinking too much water might cause swelling in their legs and just a fluid overload situation. So if the kidney function is stable, drinking too much water might not be the answer all the time. There is some evidence to suggest that linoleumid or Revlimid can worsen kidney dysfunction. So first of all, myeloma patients inherently, as you know, kidney dysfunction is a part of myeloma and it can be a presenting feature in many myeloma patients. And that's how myeloma is diagnosed for those patients, that their kidney function when the doctor did a routine blood work just shot up and maybe they didn't feel any symptoms from it, but that's what the lab showed. So that's how they came to be diagnosed. I feel sometimes in terms of the multiple myeloma, some of the medications that can ... Myeloma disease itself can provoke and cause patients to have a renal insufficiency because of the amount of protein that the body produces and how hard the kidneys have to work. And they are pretty much working double shift by clearing that protein out of the body. They are not able to compensate oftentimes just given the fact that they have additional medical issues, diabetes, high blood pressure that already is causing problems to the kidneys. But in terms of the medications, I feel like the most frequent medications that we feel need to be adjusted to with patients with a renal insufficiency are immense immunomodulating agents like lenalidomide or Revlimid is the most common one. Then the medications called bisphosphonate therapy, zoledronic acid or zomida, pomidronate or iridia. So those are the most frequent medications. If someone is undergoing the stem cell transplant and have to go through the high dose of melphalan, so the melphalan in a high dose can also cause issues to the kidneys. And this is why it requires a dose reduction for the patients with underlying kidney insufficiency. How is kidney dysfunction monitored? How do we monitor the kidney function? The kidney function is very well monitored during any chemotherapy regimen. We measure it once a week with the CMP, complete metabolic profile. You can get those numbers, you can look at them, you can trend them. It's important to know that not only multiple myeloma causes kidney damage. The way kidney function would be monitored would be again by a blood test and what we are looking for is actually serum creatinine. And that's the way we measure kidney function and based upon that value we can know if your kidneys are working right or if they are mild, moderately or severely dysfunction. It's important to, and I see it missed a lot, it's important to check the urine for the myeloma proteins for every single patient. At least a diagnosis, at least once during the treatment time or at progression. I see it missed a lot because it's a 24-hour collection, it's difficult for the patient, They have to carry a jug with them, pee in it for 24 hours, then bring it back to us. It's a long process, but I believe it gives us a lot of information. Let's say we have the proteins in the blood, again M-spike, kappa and lambda are down in the blood, they could be simply leaking through the urine. How would I know that? I have to check the urine. So kidneys, urine studies are very important in multiple myeloma. How is kidney dysfunction managed? From here on, you could tell already that the kidneys for multiple myeloma are very important and they can get injured very easily because they have to work super hard. Therefore, we start from the beginning, I try to avoid NSAIDs, means I try to avoid ibuprofen, naproxen, all the drugs that are known to cause kidney damage. I stop those drugs and we try to find alternatives to that. Typically, if your kidney function is really impaired, we would try to reduce the dose of lenatomide or even hold it till the kidney function recovers somewhat and then reintroduce the lenatomide. But formalidomide, which is its cousin, is actually better tolerated even if your kidneys are not functioning fine. Direct to moma does not seem to be affected that much by kidney dysfunction and well-paid or bortezomib also needs to be dose adjusted for your kidney dysfunction. Getting kidney doctors involved is very important. Sometimes they help us out with adjusting the blood pressure medications to help us control the kidney damage and even stop it.