A globulin blood test measures the levels of a group of proteins called globulins in blood serum. Globulins are produced by the immune system in the liver and play an important role in liver function, blood clotting, and fighting infections. The test screens for liver and kidney problems, as well as other conditions such as immune system disorders and certain types of cancer. During the test, a healthcare professional will take a blood sample from a vein in your arm using a small needle. The test measures the level of each type of protein in your blood, including the different types of globulins. The levels of specific globulins provide information about how well your immune system is working. Low globulin levels may be a sign of liver or kidney disease, or malnutrition, while high globulin levels may be a sign of infection, inflammatory disease, immune disorders, or certain cancers.