False Decrease in Uric Acid Caused by IgM Paraprotein

Background: To explore the reason and treating method for the negative value of uric acid in a patient patient. Methods: The serum of a patient with a negative uric acid detection value was diluted 5 times with "sterilized water" and with "normal saline". Additionally, the serum was treated with PEG6000 protein, and uric acid was detected. Results: Elevated IgM paraprotein in the patient resulted in abnormal uric acid response curves in serum samples or diluted serum samples. After the serum was precipitated with PEG600, the uric acid response curve was basically normal. Conclusions: The negative value of the patient's uric acid test was caused by the IgM paraprotein. After removing the interference by PEG6000 protein a true and accurate uric acid result was obtained.