The adenosine deaminase test is a test that is conducted as part of the tests to diagnose Severe Combined Immunodeficiency. This is disease that has been described as the boy in a bubble disease. In this disease, which is due to a genetic defect in a number of genes, the immune systems T cells and B cells do not mature and are therefore not available as part of the body’s adaptive immune systems. Most children born with this defect do not survive more than a year after birth due to recurrent infections; however, the problem can suddenly crop up at anytime during a person’s lifetime. Adenosine deaminase or ADA is an enzyme that has two forms ADA1 and 2. Both of these forms usually go together. ADA is present in nearly all cells and is responsible for purine metabolism to form nucleic acids. The spleen is usually the place where ADA2 is more prevalent.
The ADA test is conducted to find out whether there is too much or too little ADA in the human body by checking for serum levels of the enzyme. Too much ADA in the body will cause a condition called hemolytic anemia - a condition in which an abnormally large number of erythrocytes or red blood cells die or undergo lysis. Too little of ADA in the body will result in ADA deficiency which will cause build up of a chemical called deoxyadenosine in the blood. This combined with the resultant build up of S-adenosylhomocysteine will cause the lymphocytes, T cells, and B cells to not mature rendering the adaptive immune system useless.
There is no special preparation that needs to be done for this test though your doctor might ask you to not consume any sodium benzoate based drugs that are used for treating hyperammonemia. This is because the breakdown of adenosine will cause ammonia to be release, which will bind to sodium benzoate.
The test is conducted by taking a blood sample and then using a technique called liquid chromatography. The other, simpler test is to add some adenosine solution to blood plasma and then measuring the level of ammonia released using a standard lab test for ammonia with a Berthelot reagent. The ADA test is just one of the many tests that are conducted to conclude a case of severe combined immunodeficiency. The only way that this disease can be cured is with a bone marrow transplant.