The Albumin:Globulin (A:G) Ratio Test measures the balance between two major types of proteins in your blood:

• Albumin – made mainly by the liver; helps keep fluid in blood vessels and carries hormones, vitamins, and medicines. 
• Globulin – a group of proteins involved in immunity, blood clotting, and liver function. 

The test calculates the A:G ratio by dividing albumin level by globulin level.