Acute nephritic syndrome is a group of disorders that cause inflammation of the internal kidney structures (specifically, the glomeruli).

Acute nephritic syndrome is often caused by an immune response triggered by an infection or other disease.

Causes seen more frequently in children and adolescents include the following:

• IgA nephropathy
• Henoch-Schonlein purpura
• Hemolytic uremic syndrome
• Post-streptococcal glomerulonephritis

Associated diseases seen more frequently in adults include:

• SLE or lupus nephritis
• Membranoproliferative GN I
• Membranoproliferative GN II
• Infective endocarditis
• Vasculitis
• Rapidly progressive (crescentic) glomerulonephritis
• Goodpasture's syndrome
• Klebsiella pneumonia
• Abdominal abscesses
• Viral diseases such as mononucleosis, measles, mumps
• Typhoid fever
• Hepatitis
• Syphilis and other sexually transmitted diseases

Inflammation disrupts the functioning of the glomerulus, which is the part of the kidney that controls filtering and excretion. This inefficient functioning results in blood and protein appearing in the urine, and the accumulation of excess fluid in the body. Swelling results when protein is lost from the blood stream. (Protein maintains fluid within the blood vessels, and when it is lost the fluid collects in the tissues of the body).

Urine discoloration results from blood in the urine. This occurs because of loss of blood within the damaged glomeruli.

Acute nephritic syndrome may be associated with the development of high blood pressure, interstitial inflammation (inflammation of the spaces between the cells of the kidney tissue), and acute kidney failure.

Despite the diversity of diseases that cause acute nephritis below, they share many symptoms in common:

• Blood in the urine (urine appears dark, tea colored, or cloudy.)
• Decreased urine volume (little or no urine may be produced.)
• Swelling
  • facial swelling
  • swelling around the eye socket
  • arms, hands, feet, legs (dependent edema)
  • abdomen
  • generalized
• General aches and pains ( joint pain, muscle aches)
• General ill feeling (malaise)
• Headache
• Blurred vision
• Slow, sluggish, lethargic movement

Late symptoms include the following:

• Seizures
• Decreased alertness, drowsiness, confusion
• Nausea and vomiting
• Easy bruising or bleeding
• Cough containing mucus or pink, frothy material coughed up
• Difficulty breathing, especially at night, while lying down, or from exercise
• Flank pain
• High blood pressure

Your blood pressure may be elevated. There may be signs of fluid overload (more fluid in circulation than the heart can effectively pump), including abnormal heart and lung sounds. The jugular (neck) veins may be distended from increased pressure.

Generalized swelling is often present. When examining your abdomen, your health care provider may find signs of fluid overload and an enlarged liver. There may be signs of acute kidney failure in addition to the above symptoms.

• Urinalysis may show protein, renal tubular cells, blood, white blood cells, and casts.
• Protein in the urine test may be positive.
• Urine appearance and color are abnormal.
• Azotemia (nitrogen-containing waste products in the blood) may be evidenced by:
  • elevated BUN
  • elevated creatinine
• The creatinine clearance may be decreased.
• A potassium test may be elevated.
• A kidney biopsy reveals glomerulonephritis (inflammation of the glomeruli), which may indicate the cause.

• Culture of the throat or skin
• Blood culture
• ANA titer (lupus)
• Serum complement (C3 and C4)
• ANCA (antinutrophil cytoplasmic antibody for vasculitis)
• Anti-glomerular basement membrane antibody

The goal of treatment is to reduce glomerular inflammation. Hospitalization is required for diagnosis and treatment of many forms of acute nephritic syndrome. The cause must be identified and treated. This may include antibiotics or other medications or treatment.

Bedrest may be recommended. The diet may include restriction of salt, fluids, and potassium. Medications may include anti-hypertensive medications to control high blood pressure. Corticosteroids or other anti-inflammatory medications may be used to reduce inflammation.

Other treatment of acute kidney failure may be appropriate.

For information and support, see kidney disease support groups.

The probable outcome is variable and depends on the disease responsible for the nephritis. When improvement occurs, symptoms associated with fluid retention (such as swelling and cough) and high blood pressure may resolve in a week or two, while urine tests take months to return to normal.

Children tend to do better than adults and usually recover completely. Only rarely do they develop complications or progress to chronic glomerulonephritis.

Adults do not recover quite as well or as rapidly as children. Although recurrence is unusual, at least one-third of adults whose acute nephritic syndrome recurs will eventually develop end-stage kidney disease.

• Acute kidney failure
• Chronic kidney failure
• End-stage kidney disease
• High blood pressure
• Congestive heart failure
• Pulmonary edema
• Chronic glomerulonephritis
• Nephrotic syndrome

Call your health care provider if symptoms that are suggestive of acute nephritic syndrome develop.

Many times the disorder cannot be prevented, although treatment of illness and infection may help to reduce the risk.