Physicochemical metabolic characteristics for calcium oxalate stone formation in patients with gouty diathesis

Charles Y C Pak, Orson W. Moe, Khashayar Sakhaee, Roy D. Peterson, John R. Poindexter

Research output: Contribution to journalArticle

16 Scopus citations

Abstract

Purpose: We determined why calcium oxalate stones instead of uric acid stones form in some patients with gouty diathesis. Materials and Methods: Gouty diathesis was diagnosed from absence of secondary causes of uric acid stones or low urinary pH, and reduced fractional excretion of urate with discriminant score of the relationship between urinary pH and fractional excretion of urate less than 80. From the stone registry 163 patients with gouty diathesis were identified, including 62 with uric acid stones (GD + UA) and 101 patients with calcium oxalate stones (GD + Ca). Metabolic data and 24-hour urinary chemistry study were compared between the 2 groups. Results: Compared with GD + UA, GD + Ca had significantly greater urinary calcium (196 ± 96 mg per day vs 162 ± 82 mg per day, p <0.05) and significantly lower urinary citrate (430 ± 228 vs 519 ± 288 mg per day, p <0.05), resulting in higher urinary saturation of calcium oxalate. Both groups had low urinary pH (less than 5.5) and high urinary undissociated uric acid (greater than 100 mg/dl). Urinary calcium post-oral calcium load was significantly higher in GD + Ca than in GD + UA (0.227 vs 0.168 mg/dl glomerular filtrate, p <0.001). Conclusions: Calcium oxalate stones may form in some patients with gouty diathesis due to increased urinary excretion of calcium and reduced excretion of citrate. Relative hypercalciuria in GD + Ca may be due to intestinal hyperabsorption of calcium.

Original languageEnglish (US)
Pages (from-to)1606-1609
Number of pages4
JournalJournal of Urology
Volume173
Issue number5
DOIs
StatePublished - May 2005

Keywords

  • Calcium oxalate
  • Disease susceptibility
  • Gout
  • Uric acid
  • Urinary calculi

ASJC Scopus subject areas

  • Urology

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