Test Code #

058

CPT Code(s) #

83516

Test Name

Glomerular Basement membrane Antibody

If Profile, Includes Tests:

N/A

Disease Name:

Goodpasture Syndrome

Type of Study:

Serum Studies

Methodology:

Fluoroenzyme immunoassay (FEIA)

Substrate:

N/A

Reference Range:

Glomerular Basement Membrane (GBM) (U/mL)
• Negative < 7
• Equivocal 7-10
• Positive > 10

Units:

U/ml (Units/ml)

Schedule:

Assay performed once every week. Report availability is within one week from the time of specimen receipt

Specimen Requirements:

Collect 5-10 ml of blood in a red top or serum separator tube. If possible, separate serum from clot and place into red capped tube provided with Beutner Laboratories collection kits. If separation facilities are not available, the blood can be sent in the tube used for collection.

Sample Stability:

Sample is stable at ambient temperature during shipment. If sample is stored prior to shipment, it is stable refrigerated (2-8ºC) up to five days and frozen (-20ºC or lower) up to one year

Clinical Relevance:

Anti-glomerular basement membrane (GBM) antibody disease is a rare autoimmune disorder characterized by crescentic rapidly progressive glomerulonephritis. Tissue injury is mediated by anti-GBM antibodies that bind glomerular (and alveolar) basement membranes. The target autoantigen has been identified as the noncollagenous domain 1 (NC1) of the a3-chain of type IV collagen and is found only in basement membranes in the kidney, lung, cochlea and eye. The diagnosis of anti-GBM disease is based upon the demonstration of deposited immunoglobulins in kidney by direct immunofluorescence and detection of circulating autoantibodies. Early detection of circulating anti-GBM antibodies in the context of an acute kidney injury, with or without pulmonary hemorrhage, can direct timely initiation of treatment and improve patient outcome. The specificity and sensitivity of this assay is 100% and 94.7% respectively. Rare instances of false-positive anti-GBM antibody tests may be found in states of polyclonal activation such as in hepatitis C or HIV infection and with diverse renal pathologies. Rare cases of anti-GBM disease without circulating anti-GBM antibodies have been reported.

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