Kidney Disease and Lupus Systemic Lupus Erythematosus (SLE) can cause inflammation in major organs. Many, if not most, people with lupus may have some involvement of the kidneys. Sometimes the kidneys are not affected in a serious way, but “lupus nephritis”, a potentially serious complication of lupus, can be very grave and often requires immediate medical treatment to prevent permanent damage. Lupus nephritis has very few signs or symptoms – it can remain undetected for a long period of time. That is why it is important for people with lupus to have regular medical checkups and urine tests, even if they are feeling well or their lupus has been calm for months or years. How Lupus Affects the Kidneys Your kidneys are two bean-shaped organs located in the middle of your back, below the rib cage, one on each side of your spine. They are each about the size of a fist. The main function of the kidneys is to remove waste products and other toxins from the body. Each kidney has about one million tiny filters, or glomeruli. Each glomerulus is attached to a tubule (this glomerulus-tubule team is called a nephron). Blood is filtered in the glomerulus, and waste and extra water are collected in the tubule, where they become urine. The urine moves from the kidneys to the bladder through tubes called the ureters and is then passed out of the body. In systemic lupus, the immune system is overactive, producing antibodies to the body’s own tissues. The antibodies combine with the tissues to form immune complexes in the bloodstream. They can cause inflammation, cell death and scarring in any organ, includ- ing the kidneys, where they can get trapped by the kidneys’ filtering system. When the kidneys are inflamed, their ability to do this job is impaired, and red blood cells or proteins, which are normally kept in the blood stream by the kidneys, may leak into the urine. Tests may also show that the kidneys have lost some of the ability to remove waste products from the blood, which can become very serious. As blood proteins such as albumin are lost through the urine, their levels may drop in the bloodstream (therefore, serum albumin tests are helpful in diagnosing kidney problems). Albumin helps to regulate the amount of fluid in the body. When there is an insufficient amount of albumin, fluid can build up in the face, hands, feet or ankles and cause swelling or puffiness (edema) that may get worse as the day progresses. Symptoms of Kidney Involvement in Lupus There is usually no pain associated with kidney disease, although some patients may notice swelling in their ankles. Most often, the only indication of kidney disease is an abnormal urine or blood test, so it is important to do these tests regularly, even if you are feeling well. Warning signs include: • Large amounts of protein in the urine (proteinuria, which may cause urine to look foamy); getting up frequently to urinate during the night can be a sign of excessive protein loss. • the presence of casts in the urine (blood cells that may collect in the kidney to form and be excreted in the urine); they can be seen under a microscope 23