Membranoproliferative GN I

Definition:

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.

Alternative Names:

Mesangiocapillary glomerulonephritis (type I); Membranoproliferative glomerulonephritis (type I); Lobular GN; Glomerulonephritis - membranoproliferative (type I); MPGN type I

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 I MPGN involves deposits of antibodies in the subendothelial layer of the glomerular membrane.

Most cases of membranoproliferative glomerulonephritis are type I. (A few are type II ). Both sexes are affected. The disorder affects mostly people under age 30.

Membranoproliferative GN I may present in several forms. The glomerular membrane disruption causes a change in urine filtration, making the glomerulus permeable to protein and blood cells. This is manifested as acute nephritic syndrome , nephrotic syndrome , or abnormal urinalysis without symptoms. MPGN accounts for about 5% of all cases of idiopathic glomerulopathies (diseases of the glomerulus).

Urine output decreases because of reduced glomerular filtration rate. Swelling may occur as sodium and water are retained in the body.

Protein in the bloodstream keeps fluid within the blood vessels. Edema is increased when protein is lost because fluid leaks out of blood vessels into the tissues. Hypertension occurs due to the cumulative effects of water and sodium retention, and increased production of renin (a hormone that regulates blood pressure ) by the damaged kidney.

Nitrogenous waste products such as urea (see BUN ) and creatinine may accumulate in the blood ( azotemia ) because of poor kidney functioning. The disorder is often progressive and eventually results 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
  • decreased concentration

Signs and tests:

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. The blood pressure is often elevated.

These tests help confirm the diagnosis:

• Abnormal urinalysis :
  
  • white blood cells
  • red blood cells
  • urine protein
  • other abnormalities in the urine
• 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 I.

Treatment:

Treatment may vary according to the symptoms. Treatment goals include reduction of symptoms, prevention of complications, and slowed progression of the disorder. Steroids and cytotoxic agents have been used and may benefit certain individuals. Dipyridamole has also been used in some individuals.

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

Antihypertensive medications are critical to help control blood pressure . Diuretics or other medications may be appropriate to control swelling or other symptoms.

Dialysis or kidney transplant may eventually be required to manage kidney failure. Combination therapy with aspirin and dipyridamole may slow progression to renal failure with MPGN 1. This treatment is of unproven value.

Expectations (prognosis):

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

Complications:

• Acute renal failure
• Acute nephritic syndrome
• Nephrotic syndrome
• Chronic renal failure

Calling your health care provider:

Call for an appointment with your health care provider if symptoms indicate MPGN I may be present.

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

Prevention:

Prevention is often not possible.