A nurse is evaluating the effectiveness of allopurinol therapy for a client who has chronic gout. Which laboratory finding indicates the medication is achieving the desired therapeutic effect?

White blood cell count of 11.000/mm3 (Reference range: 4,000-11.000/mm3)

Serum creatinine level of 1.4 mg/dL (Reference range: 0.6-1.2 mg/dL)

Serum uric acid level of 5.8 mg/dL (Reference range: 3.5-7.2 mg/dL)

Blood glucose level of 130 mg/dL (Reference range: 70-110 mg/dL)