Definition of Membranoproliferative GN:

Membranoproliferative glomerulonephritis is a kidney disorder that involves inflammation and changes in the microscopic structure of kidney cells. It leads to disrupted kidney function.

Causes, incidence, and risk factors:

Glomerulonephritis is inflammation of the glomeruli, the inner structures of the kidney that help filter waste and fluids from the blood to form urine.

Membranoproliferative GN is a form of glomerulonephritis caused by an abnormal immune response. Deposits of antibodies build up in a part of the kidneys called the glomerular basement membrane. This membrane helps filter waste and extra fluid from the blood.

The changes in this membrane lead disrupt the body's ability to filter urine. Protein and fluid leak out of the blood vessels into body tissues, leading to swelling (edema). Nitrogen waste products may build up in the blood (azotemia) because of poor kidney functioning.

There are two forms of membranoproliferative GN:

• Membranoproliferative GN I
• Membranoproliferative GN II

Most cases are type I. Membranoproliferative GN II is much less common than Membranoproliferative GN I. It also tends to get worse faster than membranoproliferative GN I.

The conditions affect both men and women, mostly under age 30.