Definition of hyperuricemia and gouty conditions

To define gout conditions and hyperuricemia.

Gout is defined as an arthritic condition resulting from the deposition of monosodium urate (MSU) crystals in and/or around joints, following long-standing hyperuricemia. Several recent ultrasound studies disclosed MSU deposits in a large proportion of asymptomatic hyperuricemic patients. A gout condition defined by asymptomatic MSU deposits can therefore be individualized. Such asymptomatic deposits appear to precede the occurrence of flares, which seem to be triggered by mobilization of preformed crystals. Hyperuricemia appears to be the main, if not the only, risk factor for gout. Recent studies also support the view that hyperuricemia is an independent risk factor for renal and cardiovascular diseases. The level at which uricemia becomes abnormal is still disputed. This lack of consensus precludes comparison of studies using different definitions and impairs the understanding of gout by doctors and patients. We propose to define hyperuricemia as greater than 6 mg/dl, as the life-long risk of gout seems to start at this level. This definition is identical to the minimum uricemia target of urate-lowering drugs (ULDs).

Asymptomatic MSU crystals deposits can now be identified and precede the onset of gout flares. Defining hyperuricemia as greater than 6 mg/dl would have the advantage to give the same value for normal and ULD-targeted uricemia, which would facilitate patients' adherence to this target.