Clinical Pathology: Transfusion Medicine

• Rapidly progressive glomerulonephritis (RPGN) is a kidney disease with rapid loss of renal function and a decrease in the glomerular filtration rate of at least 50%. Histologically, crescent formation is seen in at least 50% of glomeruli.

• RPGN is separated into three categories based on immunofluorescence staining on renal biopsy. The clinical presentation, response to treatment, and prognosis differs among the three categories.

• The three categories are anti-glomerular basement membrane (GBM) antibody disease (Goodpasture disease), immune complex disease, and Pauci-immune disease.

• Anti-GBM disease is characterized by linear deposits of IgG along the GBM and is caused by an autoantibody to collagen type IV.

• From 10% to 40% of affected patients may have detectable anti-neutrophil cytoplasmic antibodies (ANCAs).

• Clinically, these patients may present with renal manifestations, including hematuria, oliguria, and anuria, and pulmonary manifestations, including cough, hemoptysis, and diffuse alveolar hemorrhage.

• Without treatment, anti-GBM disease is rapidly progressive with a high mortality rate. A combination of therapeutic plasma exchange (TPE), cyclophosphamide, and steroids is the treatment of choice and should be started as early as possible.

• Anti-GBM disease that is dialysis independent or accompanied by diffuse alveolar hemorrhage is a category I indication for TPE based on the American Society for Apheresis (ASFA) guidelines published in 2013.

• The renal dysfunction in patients with anti-GBM disease who are dialysis dependent is unresponsive to TPE and the renal damage is irreversible. This is a category IV indication for TPE.