Answer.  IgA nephropathy (IgAN or Berger’s Disease, pronounced “burr-jay” not “bur-ger” as in hamburger) results from a still not understood defect or overactivity of the immune system on which an antibody called immunoglobulin A (IgA) is deposited in glomeruli causing inflammation (called glomerulonephritis), and eventual scarring of glomeruli (called glomerulosclerosis). IgAN accounts for about 10 percent of end-stage renal disease (ESRD). Usually slowly progressive, IgAN may be relatively stable for years (basically the common IgAN that adults usually have).

Approximately 30 percent of patients progress to ESRD in 10 to 25 years. Rarely, ESRD develops in under five years. IgA nephropathy has a familial (no other family members with the disease)  attack rate in about 10 percent of cases in Kentucky and parts of the Southeast. Familial clustering of IgAN has also been reported in Southern France and Italy . Greater than 90 percent of IgA nephropathy is not familial. IgAN is most common in people of Asian ethnicity, followed by Hispanics and then Caucasians. It is least common in African Americans. IgAN is also more common in American Indians than it is in caucasians.

Most commonly diagnosed from adolescence until about age 40, IgAN is three times more frequent in boys and men than in girls and women. The discovery of blood or protein in the urine may be the first clue. A large amount of protein in the urine (heavy proteinuria) can produce a nephrotic syndrome (fluid accumulation as edema, high blood fats, low blood protein levels). Rapidly-progressive IgAN is an aggressive form that progresses to ESRD within months or more commonly, five years or less.

When a child, teenager or young adult is diagnosed with acute glomerulonephritis (or nephrotic syndrome), which eventually turns out to be IgAN (diagnosed by kidney biopsy) there are usual “flare-ups”, or episodes of visible blood in their urine, each time a respiratory infection (cold) occurs. Children with IgAN are usually treated with oral steroids (sometimes on an alternate-day basis to minimize the side effects) to halt the disease. A mild, slowly-progressing or stable chronic IgAN then continues throughout adulthood.

Though the primary cause of IgAN is not known, more than 30 other diseases can lead to IgA being deposited in the kidneys including Henoch-Schonlein purpura and lupus erythematosus. Figuring out whether a patient has one of the imitators or IgAN can be a challenge.

When IgA proteins are deposited in glomeruli, they clog blood flow causing scaring called glomerulosclerosis by the time a biopsy is performed. Ultimately, glomerulosclerosis causes permanent loss of kidney function. As more and more glomeruli become scarred and non-functional, the kidneys no longer have enough function left to perform their task of filtering waste products from the blood. When this happens, the person requires some form of renal replacement therapy, such as dialysis or a kidney transplant.

Confirmation of an IgAN diagnosis can only be made by examining a biopsy of the kidney performed through surgery. If symptoms are mild, and the serum creatinine level normal, your doctor may decide to wait some time before getting a biopsy. Some patients have 100 percent of kidney function when diagnosed, whereas previously, it was common for many patients to have already lost about 50 percent of their kidney function by the time anyone notices that something is wrong. Your doctor is most likely to order a biopsy when there is both proteinuria and hematuria, but will often do it even in the absence of proteinuria. Some nephrologists do not advise a kidney biopsy because they believe that when symptoms are mild, there is little to be gained since no treatment will be proposed. Always ask your nephrologist for a kidney biopsy, no matter how mild the symptoms are.

There is no standard treatment for chronic IgAN other than for hypertension and edema. A number of doctors believe that blood pressure medications that block an enzyme called angiotensin will protect the kidney from further damage while reducing urinary protein loss. Acute episodes with proteinuria of more than three grams per day usually improve when treated with oral corticosteroids (such as prednisone). Most doctors agree that rigorous treatment for controlling high blood pressure should be followed, as high blood pressure can contribute to the damage being caused in the kidneys and it is an independent risk factor for ESRD.

The value of a low-protein diet is controversial, as solid evidence of its value is lacking and in some cases, it can actually be harmful. An actual renal diet (low protein, low potassium, low sodium, low phosphorus, high calories) is not required until IgAN has progressed to advanced renal failure. The purpose of a renal diet is not to delay progression of IgAN, but rather to minimize symptoms of chronic renal failure. Unless you are specifically told to restrict something in your diet, there is no need to do so. Trials of drugs that slow the immune system (similar to those used to stop rejection of a kidney transplant) are now being researched, but no evidence can be supported as to which one is better than the other.

Please consider using your Internet browser to look at a wonderful Canadian Web site that now has more than 600 people with the disease registered and will provide immediate answers to your questions. The Web site is located at http://www.igan.ca.

Answer provided by Eli Friedman, MD, Chief of the Division of Renal Disease for State University of New York, Downstate Medical Center. Dr. Friedman serves as the Chairperson of the AAKP Medical Advisory Board.

The American Association of Kidney Patients presents Ask the Doctor, an opportunity for readers to submit kidney related health questions to healthcare professionals who specialize in an area of concern. The answers are not to be construed as a diagnosis and therefore, alterations in current healthcare should not occur until the patient’s physician is consulted.

This article originally appeared in the September/October 2003 issue of Kidney Beginnings: The Magazine, Vol. 2, No. 3.

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