Oral Zinc Sulfate as Adjuvant Treatment in Children With Nephrolithiasis: a Randomized, Double-Blind, Placebo-Controlled Clinical Trial

BACKGROUND: Nephrolithiasis in children is associated with a high rate of complications and recurrence. OBJECTIVES: Since some evidences reported that zinc has an important place amongst inhibitors of crystallization and crystal growth, we decided to assess the effectiveness of oral zinc sulfate as adjuvant treatment in children with nephrolithiasis. PATIENTS AND METHODS: This was a randomized, double-blind, placebo-controlled clinical trial. 102 children in the age range 1 month to 11 years with first nephrolithiasis were recruited. Patients were randomly divided into two equal groups (intervention and control groups). Intervention group received conservative measures for stones and 1 mg/kg/day (maximum 20 mg/day) oral zinc sulfate syrup for 3 months. Control group received placebo in addition to conservative measures, also for 3 months. Patients were followed up by ultrasonography for 9 months, in 5 steps (at the end of 1st, 2nd, 3rd, 6th and 9th month after treatment) assessing size and number of stones in the kidneys. RESULTS: Only at the end of the first month, the average number (intervention: 1.15 ± 3.78, control: 1.3 ± 2.84) (P = 0.001) and size (cm) (intervention: 0.51 ± 1.76, control: 0.62 ± 1.39) (P = 0.001) of stones was significantly lower in the intervention group, and in other points there was no significant therapeutic efficacy in oral zinc adjuvant treatment compared to conservative treatment alone. Also, during the 9-month follow-up, the number and size of stones in both groups decreased significantly (both: P < 0.0001) in a way that the decrease in the intervention group showed no difference with the control group. CONCLUSIONS: Adjuvant treatment with zinc is not more effective than consecutive treatment in children with nephrolithiasis. However, further studies are recommended due to the lack of clinical evidence in this field.