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

Nephritic syndrome is a type of glomerulonephritis.

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

Frequent causes in children and adolescents include the following:

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

Frequent causes 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 getting rid of wastes. This disruption results in blood and protein appearing in the urine, and the buildup of excess fluid in the body.

Swelling occurs when protein is lost from the bloodstream. (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
• Swelling of the spaces between the cells of the kidney tissue
• Acute kidney failure