GLUT1 (glucose transporter 1) is a protein that moves sugar, in the form of glucose, from the blood into cells. Pathologists test for GLUT1 to help identify certain types of tumors. It is most often used to diagnose a common noncancerous blood vessel tumor in babies called infantile hemangioma. It is also used to identify tumors that start from the lining of nerves.
GLUT1 is a test result, not a diagnosis. It is one of the stains a pathologist uses to work out what type of cells are present. This article explains why pathologists test for GLUT1 and what a positive or negative result means in your pathology report.
GLUT1 deficiency syndrome is a different condition. It is an inherited brain disorder diagnosed with blood tests, spinal fluid tests, and genetic testing, not a tissue stain. This article is about the GLUT1 stain used on tissue samples.
All cells need glucose for energy, but only some cells make large amounts of GLUT1. In normal tissue, GLUT1 is found in the following places:
Endothelial cells in most other parts of the body, such as the skin, do not contain GLUT1. This difference is what makes GLUT1 useful for diagnosing infantile hemangioma.
Pathologists test for GLUT1 using immunohistochemistry (IHC). In this test, a thin slice of tissue on a glass slide is treated with an antibody that sticks to GLUT1. A chemical reaction then colors any cell containing GLUT1 brown so that it can be seen under the microscope. GLUT1 usually outlines the edge of each positive cell.
Red blood cells in the sample stain strongly for GLUT1. They act as a built-in check that the test worked properly.
Pathologists use GLUT1 to confirm what type of cells are present. It does not predict how a tumor will respond to a particular treatment. Pathologists test for GLUT1 in the following situations:
Many cancers also contain GLUT1, especially in areas where tumor cells are short of oxygen. For this reason, clinicians do not use GLUT1 alone to determine whether a tumor is cancerous.
A positive result means the tested cells contain GLUT1. Your report may describe the result as “positive,” “reactive,” or say that GLUT1 “is expressed” by the cells.
What a positive result means depends on the question being asked:
The pathologist confirms that the stained cells are the cells of interest, and not red blood cells sitting inside or between them.
A negative result means the tested cells do not contain GLUT1. Your report may describe the result as “negative,” “nonreactive,” or “not expressed.” Red blood cells in the same sample are usually still positive, confirming the test worked.
In a blood vessel lesion, a negative result makes infantile hemangioma unlikely. It supports another diagnosis, such as a vascular malformation or pyogenic granuloma. In a nerve tumor, a negative result makes a perineurioma less likely.