None listed
Conditions
Brief summary
Objective: Studies in human volunteers have shown that vitamin C reduces serum urate (SU). The aim of this study was to determine effects of vitamin C on SU in patients with gout. Methods: Patients with gout and SU >0.36mmol/L (6mg/dl) were recruited. 20 patients already receiving allopurinol were randomised to an increase in allopurinol dose or commenced on vitamin C 500mg/d. 20 patients not receiving allopurinol were randomised to start allopurinol or vitamin C 500mg/d. Plasma ascorbate, creatinine, and SU were measured at day 0 and week 8. Results: There was no significant difference in baseline SU or eGFR between those who received vitamin C and those who did not (SU 0.50+/-0.11mmol/l (8.4 +/- 1.8mg/dl) vs. 0.50+/-0.09mmol/l (8.4 +/-1.5mg/dl) p=0.89; eGFR 65.5+/-15.7ml/min/1.73m2 vs. 67.9+/-20.7 ml/min/1.73m2 p=0.67). 30% in the vitamin C group and 25% in the no vitamin C group were receiving diuretics (p=0.72). In the patients receiving vitamin C there was a significant increase between week 0 and 8 in plasma ascorbate. The reduction in SU was significantly less in those patients receiving vitamin C compared to those who started or increased the dose of allopurinol (0.014mmol/l (0.23mg/dl) vs. 0.118 (1.9mg/dl) mmol/l p<0.001). Conclusion: Modest dose vitamin C (500mg/d) for 8 weeks had no clinically significant urate lowering effect in patients with gout despite increasing plasma ascorbate. These results differ from findings in hyperuricaemic healthy controls. The uricosuric effect of modest dose vitamin C appears less in patients with gout both as monotherapy and in combination with allopurinol.
Interventions
Forty patients with gout and persistent hyperuricaemia (serum urate >0.36mmol/L) will be recruited. Patients not already receiving allopurinol will commence either oral vitamin C 500mg/d or oral allopurinol. The dose of allopurinol will be determined by the treating physician based on renal function to achieve a target serum urate of <0.36mmol/L. It is anticipated that the dose of allopurinol will be between 100 and 600mg/day. Patients already receiving allopurinol will have the dose of allopuri
Forty patients with gout and persistent hyperuricaemia (serum urate >0.36mmol/L) will be recruited. Patients not already receiving allopurinol will commence either oral vitamin C 500mg/d or oral allopurinol. The dose of allopurinol will be determined by the treating physician based on renal function to achieve a target serum urate of <0.36mmol/L. It is anticipated that the dose of allopurinol will be between 100 and 600mg/day. Patients already receiving allopurinol will have the dose of allopurinol increased (by 50-100mg/day) as determined by the physician based on renal function or commence oral vitamin C 500mg/d. The overall duration of the vitamin C intervention will be 8 weeks. Allopurinol will be continued as it remains the standard treatment for gout after the 8 week period.
Sponsors
Associate Professor Lisa Stamp
Study design
Allocation
Randomised controlled trial
Intervention model
Parallel
Primary purpose
Treatment
Masking
Open (masking not used)
Eligibility
Sex/Gender
All
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
Gout as defined by American Rheumatology Association (ARA) preliminary classification criteria and a serum urate of >0.36mmol/L
Exclusion criteria
Patients taking regular vitamin supplements will be excluded.
Outcome results
None listed