Mar. 06, 2014

Lupus in the Kidney: What are the risks and what can be done about it?

by Dr. Joan T. Merrill, Lupus Foundation of America Medical Director

When lupus affects the kidney it can be a difficult time. I try to think about what a person experiences when they get that first call from their doctor that their tests are not looking so good, and they might have nephritis. Maybe there is protein in the urine, maybe certain other blood tests are positive, and usually the first thing that happens is that some sort of retesting is done. Then a kidney biopsy is ordered.  When the results come in, decisions have to be made and almost always some new medication is started.  The medication often has significant side effects but that’s not the worst part. The worst part is the fact that you often have to wait three to four (or even more) months before it is clear whether the treatment is having any effect. Sometimes several different medications have to be tried to get the kidneys under control. Sometimes nothing works quite well enough, and eventually some people end up needing a kidney transplant.  Even when there is a good response early on in the treatment process, the need to continue these toxic treatments could go on and on, and it may begin to feel as if life will never get back to normal.

Is there a road map for any of this? The good news is that enough progress has been made in recent years that the American College of Rheumatology and the American Society of Nephrology have issued guidelines to help doctors optimize their monitoring and treatment of lupus nephritis. The first concern is to determine if a person is at high risk for kidney inflammation.  Anybody with lupus can potentially get one or more forms of kidney involvement, but people with lupus who have antibodies to double stranded DNA (anti-dsDNA) and low complement proteins (on a lab test sheet the one to look for in particular is called C3) and patients of South American, Asian or African descent have increased risk and should be watched more carefully for warning signs.

Usually the earliest sign is when the protein increases in a sample of urine. Of course this sometimes happens for reasons that are not due to lupus. Certain treatments that are commonly used in lupus such as ibuprofen or naproxen can cause reversible protein in the urine. Street drugs such as cocaine, dehydration, excessive exercise, toxins, diabetes and many other conditions can also cause protein to spill in a urine sample. Sometimes there are other factors in the urine such as red blood cells or white blood cells. These are less helpful because they too can be from many causes and often they are not seen even when there is nephritis. Rarely, the red blood cells will be found clumped together in the shape of one of the kidney tubules they originally formed in. This is called a red blood cell cast and it is a very helpful finding because it almost always means there is lupus nephritis.

Often, though, protein in the urine is the only early sign of lupus in the kidney. Therefore, if there are no other risk factors and if the protein does not go away on retesting it is very important to get a kidney biopsy as soon as possible. This is because getting treated for lupus nephritis right away is very important, and without a proper diagnosis the wrong treatment could be given. And these treatments can be toxic. Even within the spectrum of lupus, there are different forms of nephritis. In fact protein in the urine can also be caused by blood clots from a lupus-related condition called the antiphospholipid syndrome, which should be treated with anticoagulation. Since this can occur both with and without nephritis, which requires immune suppressants, this underscores the importance of the biopsy. It is also important to get a biopsy to see if there is already kidney damage before treatment is started. This is rated on a scoring system called a chronicity scale. If there is already damage to the kidney, it is harder to get the best results with treatment. On the other hand, if there is no chronicity, it can be very reassuring that the nephritis was caught early and the chances of success with treatment are very good.

Right now there are a number of new diagnostic tests being developed in the hopes that, in the future, biopsies can be avoided, and accurate diagnosis and treatments might be started even earlier. There are also some potentially powerful new treatments in development. There is even some speculation that certain new drugs that are being developed to reduce fibrosis might someday be tested to reverse chronicity that has already occurred in the kidney. Therefore there is a lot of hope on the horizon. In the meantime, the key to dealing with lupus kidney disease is knowing if you might be at higher risk, getting regular monitoring, and getting the earliest possible diagnosis and treatment, should it occur.

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