By Silvia German, RN, CNN, Education Manager with the DaVita® National Clinical Education Team
Disclaimer: This article is for informational purposes only and is not intended to be a substitute for medical advice or diagnosis from a physician.
Light-chain deposition disease (LCDD) is a rare disorder occurring most often during the sixth decade of life. LCDD always affects the kidneys, among other organs. But first, a light chain itself should be explained.
Our immune system produces antibodies, or immunoglobulins, to identify and eliminate foreign invaders such as bacteria and viruses, also called antigens. The immunoglobulins have the shape of a Y and are typically made of two heavy and two light chains. The body of the Y is made by the two heavy chains and the two light chains attach left and right to the Y’s arms. Together, the two pairs of chains produce a specific shape at each tip of the Y that is designed to capture a specific antigen. The antigen’s shape fits the shape of the antibody, similar to how a key fits into a lock.
Plasma cells are a type of white blood cells found in the bone marrow that produce light chains.
LCDD is a disorder that can occur when these plasma cells start producing far too many light chains in an uncontrolled manner. The light chains circulate in the blood and are then deposited in various organs. The kidneys are always involved, but deposits can also occur in the liver, heart, small intestine, spleen, skin, nervous system and bone marrow.
LCDD is a rare disorder and the true rate of occurrence is not known. While the age of people getting the disorder ranges from about 30 to 90 years, it most often occurs after the 60th birthday and males seem to get it at a higher rate than females. About 50 to 60 percent of those who develop LCDD also have multiple myeloma, a cancer of the plasma cells in the bone marrow. The remaining people do not have other blood disorders typically, or they may be diagnosed with monoclonal gammopathy of unknown significance (MGUS), a condition that causes plasma cells to produce an abnormal protein, but one that doesn’t seem to cause problems.
Within the kidneys, LCDD causes glomerulosclerosis, a scarring of the kidneys’ tiny blood vessels. Signs and symptoms include nephrotic syndrome with proteinuria,low levels of blood serum protein, high levels of blood lipids and swelling or edema. The loss of kidney function is similar to that seen with diabetic kidney disease. If the heart is involved, it can cause enlargement, congestive heart failure and irregular heartbeat. Deposits in the liver usually cause no symptoms; however, liver failure in rare cases has been reported. Peripheral neuropathy with pain, loss of sensation or an inability to control muscles can develop if the nervous system is involved, and if light chains are deposited in the skin, lesions can appear.
LCDD is often found when a person is evaluated for proteinuria or nephrotic syndrome and a renal biopsy is performed. The tiny piece of removed kidney tissue is examined under an electron microscope and light chains deposited in the kidney can be seen. About 85 percent of people with LCDD also have light chains in their blood or urine, which can be detected through immunoelctrophoresis or immunofixation, tests that measure the amount of immunoglobulins in the blood or urine. For those without light chains in their blood or urine, bone marrow can aspirate to look for abnormal numbers of plasma cells or for the presence of large amounts of light chains. By staining the bone marrow with fluorescent dye, known as immunofluorescence, the faulty plasma cells can be viewed under a microscope.
The treatment goal for LCDD is to reduce those plasma cells responsible for the overproduction of immunoglobulin light chains. This is sometimes done with the use of chemotherapy, such as a combination of prednisone and melphalan hydrochloride (Alkeran®). Another possible option is a stem cell transplant. Stem cells are immature blood cells that can change into different specialized cells such as red blood cells, white blood cells and platelets (needed for blood clotting). A person’s own stem cells are first collected and preserved from the blood or the bone marrow. Next, the patient receives high doses of chemotherapy to destroy the abnormal plasma cells. Thereafter, the preserved stem cells are infused into the patient’s blood where they migrate to the bone marrow and start producing healthy plasma cells.
If the person with LCDD progresses to kidney failure, dialysis is needed to replace the lost kidney function. A transplant may also be considered, however, the risk of LCDD recurrence in the transplanted kidney is up to 80 percent. Therefore a stem cell transplant is first required before a person with LCDD could get a kidney transplant.
Because LCDD is uncommon, no standard treatment has been established. If untreated, about 70 percent of people with LCDD will progress to kidney failure and require dialysis. Survival from the time LCDD is diagnosed has ranged from one month to 10 years. Studies suggest that chemotherapy with stem cell transplantation may be the best treatment for LCDD.This treatment has been shown to result in longer survival, normalization of the blood serum free light-chain levels and even reversal of organ damage. For people on dialysis considering a kidney transplant, chemotherapy with stem cell transplant is beneficial to prevent recurrence of light-chain deposits in the transplanted organ.
This site is for informational purposes only and is not intended to be a substitute for medical advice from a physician.
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