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Time required for disappearance of urate crystals from synovial fluid after successful hypouricaemic treatment relates to the duration of gout
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  1. Eliseo Pascual1,
  2. Francisca Sivera2
  1. 1Hospital General Universitario de Alicante, and Universidad Miguel Hernández, Alicante, Spain
  2. 2Hospital General Universitario de Alicante, Spain
  1. Correspondence to:
    Dr E Pascual
    Catedrático de Medicina (Reumatología), Hospital General Universitario de Alicante, Maestro Alonso 109, 03010 Alicante, Spain; pascual_eli{at}gva.es

Abstract

Objectives: To determine whether hypouricaemic treatment results in the disappearance of urate crystals from gouty joints and to define the time required.

Methods: In 18 patients with monosodium urate (MSU) crystal proven gout, and after the initiation of successful serum uric acid (SUA)-lowering treatment, an arthrocentesis of the asymptomatic signal joint (11 knees, 7 first metatarsophalangeal joints) was performed every 3 months to obtain a synovial fluid (SF) sample. The sample was then analysed for the presence of MSU crystals, and the number of crystals/400× field was noted. SUA levels and the duration of gout were also noted.

Results: MSU crystals disappeared from the SF of all 18 joints after reduction of SUA to normal levels. The time required for disappearance ranged from 3 to 33 months; disappearance time correlated with the duration of gout (rs = 0.71; p<0.01). The median number of MSU crystals in the SF samples before urate-lowering treatment was 7.5 (2.5–11) crystals/400× field, reducing to 3 (1–6.5) crystals/400× field (p<0.05) at 3 months. Crystal counts continued to decrease after 3 months.

Conclusions: In gout, reduction of SUA to normal levels results in disappearance of urate crystals from SF, requiring a longer time in those patients with gout of longer duration. This indicates that urate crystal deposition in joints is reversible. Normalisation of SUA levels results in a decrease in the concentration of MSU crystals in SF in the asymptomatic gouty joints. This may partially explain the reduced frequency of gouty attacks when a patient has been treated with SUA-lowering drugs.

  • MTP, metatarsophalangeal
  • MSU, monosodium urate
  • SF, synovial fluid
  • SUA, serum uric acid
  • gout
  • monosodium urate crystals
  • synovial fluid
  • gout treatment

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Footnotes

  • Published Online First 12 January 2007

  • Conflict of interest: None declared.

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