Membranoproliferative glomerulonephritis type I is a kidney disorder that results in disrupted kidney function, caused by inflammation and changes in the microscopic structure of kidney cells.

See also: Membranoproliferative GN II

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 I is a form of glomerulonephritis. It is 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 edema. Nitrogen waste products may accumulate in the blood (azotemia) because of poor kidney functioning.

The disorder is often progressive and eventually results in chronic renal failure.

Most cases of membranoproliferative glomerulonephritis are type I. The conditions affects both men and women, mostly people under age 30.

• Blood in the urine
• Dark urine (smoke, cola, or tea colored)
• Cloudy urine
• Decrease in urine volume
• Swelling of any part of the body
• Changes in mental status such as decreased alertness or decreased concentration

The results of a physical examination vary depending on the symptoms. Swelling may be present along with signs of fluid overload, such as abnormal sounds when listening to the heart and lungs with a stethoscope.

Blood pressure is often high because of increased water and sodium (salt) retention and and increased production of renin, a hormone that controls blood pressure.

Membranoproliferative GN I may present in several forms. It may be seen as acute nephritic syndrome, nephrotic syndrome, or an abnormal urinalysis without symptoms.

These tests help confirm the diagnosis:

• Urinalysis
• Urine protein
• BUN and creatinine
• Serum complement levels
• Serum complement C3 nephritic factor

A kidney biopsy confirms the diagnosis of membranoproliferative GN I.