Method: Enzymatic Method



Adenosine deaminase (ADA) assay kit is for determination of ADA activity in human serum samples. ADA is an enzyme catalyzing the deamination reaction from adenosine to inosine. The enzyme is widely distributed in human tissues, especially high in Tlymphocytes. Elevated serum ADA activity has been observed in patients with acute hepatitis, alcoholic hepatic fibrosis, chronic active hepatitis, liver cirrhosis, viral hepatitis and hepatoma. Increased ADA activity was also observed in patients with tuberculous effusions. Determination of ADA activity in patient serum may add unique values to the diagnosis of liver diseases in combination with ALT or γ-GT (GGT) tests. ADA assay may also be useful in the diagnostics of tuberculous pleuritis.


The ADA assay is based on the enzymatic deamination of adenosine to inosine which is converted to hypoxanthine by purine nucleoside phosphorylase (PNP). Hypoxanthine is then converted to uric acid and hydrogen peroxide (H2O2) by xanthine oxidase (XOD). H2O2 is further reacted with TOOS and 4-aminoantipyrine (4-AA) in the presence of peroxidase (POD) to generate quinone dye which is monitored in a kinetic manner.


The assay is linear up to ADA concentration of 200U/L. Sample above this concentration should be diluted 1+1 with 0.9% NaCl and reassay. Multiply the result by 2.


The following
analytes were tested up to the levels indicated and found not to interfere:
Hemoglobin: up to 800 mg/dl
Intralipid: up to 1000 mg/dl
Ascorbic acid: up to 50 mg/dl


The minimum detectable concentration of ADA with an acceptable level of precision was determined as 1 U/L.


The CV of the test should be less than 5%.