deoxyuridine suppression test (dUST)

Indications

• folate deficiency
• vitamin B12 deficiency (perhaps indirectly)

Principle

the test uses radiolabel & requires bone marrow aspiration

dUMP is converted to dTMP by thymidilate synthase, an enzyme that uses N5,N10-methylenetetrahydrofolate as a cofactor.

The test measures the impaired ability of deoxyuridine to suppress incorporaton of tritiated thymidine into DNA of cultured bone marrow cells

       thymidylate                            DNA
       synthase                               pol
dUMP   ----------->   thymidine + thymidine*  ---->  DNA

* The test based upon competition of unlabeled thymidine synthesized from dUMP with added tritiated thymidine. It measures thymidylate synthase activity which uses N5,N10-methylenetetrahydrofolate as a cofactor.

Addition of cobalamin or various folates to culture may help sort out the deficiency

More general terms

• special chemistry test

Additional terms

• deoxyuridine
• folic acid; folate; vitamin B9
• N5,N10-methylenetetrahydrofolate
• thymidylate synthase; TS; TSase (TYMS, TS, OK/SW-cl29)
• vitamin B12; cobalamin