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How low has serum uric acid got to be?

 

Clinical bottom line

To alleviate attacks of gouty arthritis and remove uric acid crystals from synovial fluid, serum uric acid has to be kept below 6 mg/dL (360 µmol/L).


Reference

J Li-Yu et al. Treatment of chronic gout. Can we determine when urate stores are depleted enough top prevent attacks of gout? Journal of Rheumatology 2001 28: 577-580.

Study

This prospective study involved 57 men with crystal-proven gout, who had been started on allopurinol, and with a follow up of 2-10 years at the Veteran Affairs Medical centre in Philadelphia. All were initially hyperuricaemic, and the treatment goal of patients and physicians was to increase the dose of allopurinol until the serum uric acid was below 6 mg/dL, and to maintain this level for at least 12 months. At that time knee aspiration was performed, and was performed also in men who did not achieve the target level of uric acid.

Results

There were 19 men who achieved the target, and 38 who did not.

In the 19 men achieving the target:

In the 38 men achieving the target:

Comment

There is more in the paper than this, mostly further examinations of data on small numbers of men, for instance with and without tophi, but numbers were so small as not to make much sense. There are some interesting comments about the presence or absence of synovial fluid crystals and clinical signs. Most important, this is one of the few papers addressing the question of how low serum uric acid has to be driven.