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:

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

The inflammation disrupts the functioning of the glomerulus, which is the part of the kidney that controls filtering and excretion. This disruption results in blood and protein appearing in the urine, and the build up 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). Blood loss from the damaged kidney structures leads to blood in the urine.

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

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

Late symptoms include the following:

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

Your blood pressure may be high. When examining your abdomen, your health care provider may find signs of fluid overload and an enlarged liver. When listening to your lungs and chest with a stethoscope, abnormal heart and lung sounds may be heard. The neck veins may be enlarged from increased pressure.

Generalized swelling is often present. There may be signs of acute kidney failure.

Tests that may be done include:

• BUN
• Creatinine
• Creatinine clearance
• Urinalysis
• Urine appearance and color
• Potassium test
• Protein in the urine

A kidney biopsy reveals inflammation of the glomeruli, which may indicate the cause.

Tests to determine the cause of the acute nephritic syndrome may include:

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