Adenosine Deaminase, Blood
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Adenosine deaminase (ADA) catalyzes the deamination of adenosine to inosine, an important mechanism for regulating the quantity of adenosine nucleotides (eg, adenosine triphosphate [ATP]) within the red cell. Some congenital hemolytic anemias with markedly elevated (50-70 x normal) ADA activity are associated with reduced concentrations of ATP. This hemolytic disorder is inherited in an autosomal dominant pattern, in contrast to most erythrocyte enzymopathies. Elevated ADA is also seen in Diamond Blackfan anemia (DBA) and may be used as supportive evidence in the differential diagnosis of transient erythroblastopenia of childhood. Approximately 20% of severe combined immunodeficiency disease (SCID) patients are associated with ADA deficiency. This test can be used in combination with clinical features and corroborative laboratory testing to support a diagnosis subtype for suspected SCID patients.
Evaluation of hemolytic anemia of obscure cause
Evaluation of severe combined immunodeficiency syndrome
In hemolytic anemia due to adenosine deaminase (ADA) excess, ADA concentrations are 48 to 100 U/g hemoglobin.
In severe combined immunodeficiency syndrome, ADA concentrations are <0.3 U/g hemoglobin.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
This test should not be used for monitoring patients receiving PEG-adenosine deaminase (ADA) therapy.
The limit of detection of this assay is such that the result of this test should not be used as an independent diagnostic test for adenosine deaminase deficiency. If clinical or family history or presentation is suggestive of a severe combined immunodeficiency syndrome or variant severe combined immunodeficiency disease, consultation with a clinical immunologist is recommended along with additional testing for lymphocyte subset quantitation (TBBS / T- and B-Cell Quantitation by Flow Cytometry) to determine the immune phenotype. As the diagnostic window is very narrow for this test, some normal healthy individuals can have values below the limit of detection.
Mayo Medical Laboratories does not offer ADA testing on pleural fluid. If looking to rule out tuberculosis, we recommend MTBRP / Mycobacterium tuberculosis Complex, Molecular Detection, PCR assay. That test is FDA approved for respiratory specimens only, but can be performed on other specimen types.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
0.5-1.7 U/g Hb
Clinical References Provides recommendations for further in-depth reading of a clinical nature
1. Fairbanks VF, Klee GG: Biochemical aspects of hematology. In Tietz Textbook of Clinical Chemistry. Third edition. Edited by CA Burtis, ER Ashwood, Philadelphia, WB Saunders Company, 1999, pp 1642-1646
2. Hirschhorn R: Adenosine deaminase deficiency and immunodeficiencies. Fed Proc 1979;36:2167-2170
3. Hirschhorn R: Overview of biochemical abnormalities and molecular genetics of adenosine deaminase deficiency. Pediatr Res 1993 Jan;33(1 Suppl):S35-41