Abstract:

Objective To explore the possible interference factors in the measurement of serum uric acid （UA）by uricase-peroxidase coupled reaction and the methods to eliminate these interference factors. Methods: Two cases with pseudo-hypouricemia detected by uricase-peroxidase coupled reaction were analyzed. Causes for interference on measurement were analyzed via alarm message and reaction curve displayed on the instrument. Different approaches were adopted to eliminate the interference on measurement of serum UA. Results: The initial measurement value of serum UA for case 1 was 18.2 μmol/L. According to the reaction curve, it was speculated that the low UA value might be caused by the admi-nistration of Rasburicase. Thereafter, the blood sample withdrawn from case 1 was recollected into pre-cooled heparin tube, and the corrected value was 102.0 μmol/L. The initial measurement value of serum UA of case 2 was a negative value, the reaction curve and appearance of protein precipitation in in-vitro test indicated that the internal M protein was suspected to lead to the false decrease of serum UA value. The UA value of case 2 was normalized to 158.5 μmol/L via the PEG6000 protein precipitation method. Conclusions: Measurement of serum UA by uricase-peroxidase coupled reaction may be affected by various exogenous and endogenous factors. When the UA value comes to be abnormal, comprehensive analysis of reaction curve is needed to confirm the interference factor, which helps to achieve more accurate test results in clinical setting.

Key words: Uric acid, Rasburicase, M Protein, Interference