Membranoproliferative GN II

Membranoproliferative GN II

Definition:

A kidney disorder causing decreased kidney function because of inflammation and changes in the tissues of the internal kidney structures.

Alternative Names:

Membranoproliferative glomerulonephritis (type II); Glomerulonephritis - membranoproliferative (type II); Mesangiocapillary glomerulonephritis (type II); Dense deposit disease; MPGN II

Causes, incidence, and risk factors:

The glomeruli are the inner structures of the kidney. They include small capillaries surrounded by membranes through which the blood is filtered to form urine. Glomerulonephritis involves inflammation of the glomeruli. Membranoproliferative glomerulonephritis (MPGN) is a form of glomerulonephritis caused by an abnormal immune response, with deposits of antibodies in the kidneys. Certain cells in the capillary wall (mesangial cells) increase in number and the parts of the glomerular membranes change in structure. Type II MPGN involves deposits within the glomerular basement membrane (the "bottom" layer of the membrane).

Membranoproliferative GN II is much less common than MPGN I. Both sexes are affected. The disorder affects mostly persons under age 30.

The effect of the disorder is very similar in both forms of MPGN. The glomerular membrane changes make the glomerulus permeable to protein and blood cells. The microscopic features of MPGN II are somewhat more variable and cellular compared to MPGN I. MPGN II also tends to have a more rapid progression to end stage renal disease than does MPGN I.

MPGN may present as acute nephritic syndrome, nephrotic syndrome, or abnormal urinalysis without symptoms. It accounts for less than 5% of all cases of idiopathic (unexplained) glomerulopathies (glomerular diseases). White blood cells may be excreted in the urine, causing it to have a cloudy appearance. Urine output decreases as glomerular filtration rate (the "speed" of blood purification) reduces.

Swelling of the body may occur as sodium and water are retained in the body. Protein in the bloodstream normally keeps fluid within the blood vessels. When protein is lost, fluid leaks from blood vessels into the tissues, which contributes to edema.

Hypertension occurs from the cumulative effects of water and sodium retention and increased production of renin (a hormone that regulates blood pressure) by the damaged kidney.

Nitrogen-containing waste products such as urea and creatinine may accumulate in the blood (azotemia) when kidney function is poor. These waste products are toxic to the tissues of the body. The disorder is often progressive and may result in chronic renal failure.

Symptoms:

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, decreased alertness and concentration

Note: Symptoms are variable.

Signs and tests:

The results of a physical examination vary depending on the symptoms of the disorder. Edema is common, along with signs of fluid overload such as abnormal sounds on auscultation of the heart and lungs. The blood pressure is often elevated.

These tests help confirm the diagnosis:

abnormal urinalysis:
- white blood cells, urine
- red blood cells in urine
- protein, urine
- or other abnormalities.
possible increase in BUN and creatinine, indicating decreased kidney function.
possible decrease in serum complement levels indicating immune system involvement.
possible presence of serum complement C3 nephritic factor.

A kidney biopsy confirms the diagnosis of membranoproliferative glomerulonephritis type II.

Treatment:

Treatment may vary according to the symptoms. Treatment goals include reduction of symptoms, prevention of complications, and slowed progression of the disorder.

Dietary adjustments may include restrictions on sodium, fluids, protein, or other restrictions to control high blood pressure, swelling, and accumulation of waste products in the bloodstream.

Antihypertensive medications may be vital to help control blood pressure. Diuretics or other medications may be needed to control edema or other symptoms.

Dialysis or kidney transplantation may eventually be required to manage renal failure.

Expectations (prognosis):

The disorder progresses slowly to chronic renal failure. Fifty percent of cases will develop chronic renal failure within 10 years.

Complications:

Calling your health care provider:

Call for an appointment with your health care provider if symptoms indicate MPGN II.

Call for an appointment with your health care provider if symptoms worsen or new symptoms develop, including decreased urine output.

Prevention:

Prevention is often not possible.

Review Date: 12/1/2001
Reviewed By: Andrew Koren, M.D., Department of Nephrology, NYU-Mount Sinai Medical Center, New York, NY. Review provided by VeriMed Healthcare Network.

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