Lupus in the kidney: Risks and warning signs
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 indicate 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.
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.
Anyone with lupus can potentially get one or more forms of kidney involvement.
People with the following risk factors should be watched more carefully for warning signs:
- presence of antibodies to double stranded DNA (anti-dsDNA)
- low complement proteins (on a lab test sheet the one to look for in particular is called C3)
- patients of South American, Asian or African descent
Warning signs of nephritis
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, as well as dehydration, excessive exercise, toxins, diabetes and many other conditions can also cause protein to spill into a urine sample.
Sometimes there are other elements that show up in 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.
The diagnostic role of a kidney biopsy
Getting treated for lupus nephritis right away is very important. Without a proper diagnosis, however, 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 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.
Future treatments mean hope on the horizon
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.
Joan T. Merrill, MD
Chief Advisor, Clinical Development
As Chief Advisor for Clinical Development, Dr. Merrill focuses on developing a new approach to evaluating patient progress in clinical trials and clinical practice. Read Bio