Lead chelation therapy and urate excretion in patients with chronic renal diseases and gout

Background. It is known that chronic renal insufficiency (CRI) patients wit h gout may have subtle lead poisoning. In addition, gout episodes Frequentl y aggravate progressive renal insufficiency because of the use of nephrotox ic drugs and urate deposition. Our study was arranged to evaluate the causa l effect of environmental lead exposure on urate excretion in CRI patients. Methods. A cross-section study and a randomized. controlled trial were perf ormed. Initially. 101 patients with CRI and without a history of previous l ead exposure received ethylenrdiamine-tetraacetic acid mobilization tests t o assess body lead stores (BLS). Then. a clinical trial was performed: 30 C RI patients with gout and high-normal BLS and the changes of urate excretio n in these patients were compared before and after lead chelating therapy. The treated group received four-week chelating therapy, and the control gro up received a placebo therapy. Results. The BLS of patients with CRI and gout was higher than that of pati ents with CRI only, and none had subtle lead poisoning. The BLS. not the bl ood lead level (BLL), significantly correlated to indices of urate: excreti on in all CRI patients after related factors were adjusted. In addition, af ter lead chelating therapy, urate clearance markedly improved after a reduc tion of the BLS of patients with CRI and gout (study group 67.9 +/- 80.0% v s, control group 1.2 +/- 34.0%. P = 0.0056). Conclusion. Our findings suggest that the chronic low-level environmental l ead exposure may interfere with urate excretion of CRI patients. Importantl y, the inhibition of urate excretion can be markedly improved by lead chela ting therapies. These data shed light on additional treatment of CRI patien ts with gout: however, more studies are needed to confirm our findings.