IgA nephropathy usually doesn't cause symptoms in the early stages. The disease can go unnoticed for decades and is sometimes first suspected when routine tests reveal protein and red blood cells in your urine that can't be seen without a microscope (microscopic hematuria).

Signs and symptoms of IgA nephropathy when kidney function is impaired include:

• Cola- or tea-colored urine (caused by red blood cells in the urine)
• Repeated episodes of cola- or tea-colored urine, sometimes even visible blood in your urine, usually during or after an upper respiratory or other type of infection
• Pain in the side(s) of your back below your ribs (flank)
• Swelling (edema) in your hands and feet
• High blood pressure

Your kidneys are two bean-shaped, fist-sized organs located at the small of your back, one on each side of your spine. Each kidney contains tiny blood vessels (glomeruli) that filter waste, excess water and other substances from your blood as they pass through your kidneys. The filtered blood re-enters your bloodstream, while the waste material passes into your bladder and out of your body when you urinate.

Immunoglobulin A (IgA) is an antibody that plays a key role in your immune system by attacking invading pathogens and fighting infections. But in IgA nephropathy, this antibody collects in the glomeruli, causing inflammation (glomerulonephritis) and gradually affecting their filtering ability.

Researchers don't know exactly what causes IgA deposits in the kidneys, but these conditions or factors may be associated with the development of IgA nephropathy:

• Genes, because IgA nephropathy is more common in some families and in certain ethnic groups
• Liver diseases, including cirrhosis, a condition in which scar tissue replaces normal tissue within the liver, and chronic hepatitis B and C infections
• Celiac disease, a digestive condition triggered by eating gluten, a protein found in most grains
• Dermatitis herpetiformis, an itchy, blistering skin disease that stems from gluten intolerance
• Infections, including HIV infection and some bacterial infections

Although the exact cause of IgA nephropathy is unknown, these factors may increase your risk of developing this condition:

• Sex. In North America and western Europe, IgA nephropathy affects at least twice as many men as it does women.
• Ethnicity. IgA nephropathy is more common in Caucasians and Asians than it is in blacks.
• Family history. In some cases, IgA nephropathy appears to run in families, indicating that genetic factors may contribute to the disease.

The course of IgA nephropathy varies from person to person. Some people have the disease for years with few problems. In fact, many cases may go undiagnosed. Other people develop one or more of the following complications:

• High blood pressure. Damage to your kidneys from IgA deposits can raise your blood pressure, and high blood pressure can cause further damage to your kidneys.
• High cholesterol. High levels of cholesterol may increase your risk of a heart attack.
• Acute kidney failure. If your kidneys lose their filtering ability due to IgA deposits, waste products build up quickly in your blood.
• Chronic kidney disease. IgA nephropathy can cause your kidneys to gradually stop functioning. In such cases, permanent dialysis or a kidney transplant is needed to sustain life.
• Nephrotic syndrome. This is a group of problems that can be caused by damage to the glomeruli, including high urine protein levels, low blood protein levels, high cholesterol and lipids, and swelling of your eyelids, feet and abdomen.