Glial Fibrillary Acidic Protein (GFAP)

Test Code

14319

CPT Codes
83520

Preferred Specimen

0.7 mL plasma collected in an EDTA (lavender-top) tube

Patient Preparation
Patients should be cautioned to stop biotin consumption at least 72 hours prior to collection of a sample

Minimum Volume

0.5 mL

Other Acceptable Specimens

Serum

Instructions

Draw blood in an EDTA (lavender-top) tube (invert to mix with preservatives) or serum separator tube or red-top (no gel) tube. Centrifuge and transfer plasma or serum to a labeled plastic transport tube. Specify sample type collected on tube.

Transport Container

Transport tube

Transport Temperature

Room temperature

Specimen Stability

Room temperature: 43 days
Refrigerated: 43 days
Frozen: 40 days

Methodology
Electrochemiluminescence Immunoassay

Setup Schedule

Set up: Tues-Sat; Report available: 2-4 days

Reference Range

<20 years	Not Established
20-39 years	<68.9 pg/mL
40-49 years	<74.2 pg/mL
50-59 years	<86.5 pg/mL
≥60 years	<156.9 pg/mL

Clinical Significance

Glial fibrillary acidic protein (GFAP) is a protein expressed in astrocytes, cells that support neurons and help form the blood-brain barrier, found within the central nervous system (CNS) and is involved in several important CNS processes. It is a marker of astrogliosis and is upregulated in the brain as a result of attempts at repair and the formation of a glial scar. Glial scarring occurs as a result of several neurodegenerative processes, including Alzheimer's disease, multiple sclerosis, and neuromyelitis optica. It can also be seen after damaging pathological events such as traumatic brain injury and stroke [1]. Increased presence of GFAP can also be observed in association with brain tumors such as glioblastoma multiforme [2]. GFAP expression is known to decrease in disorders such as schizophrenia, bipolar disorder, and depression [3].

1. Nature Reviews Neurology 18(3):158-172.
2. J Neuro Sci 35 (1):147-155.
3. Molecular Psychiatry 5(2):142-149.

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.