Data will be collected and tabulated using the commercially available SPSS software version 17 (SPSSInc, Chicago, IL, USA). Descriptive statistics will be presented in terms of percentage, frequency, means and standard deviations for parametric variables and median with interquartile ranges for non-parametric. Differences between both groups will be compared with the Fisher's exact test for categorical data and Student's t- test for the continuous variables. In addition, interplay of more than 2 variables will be analysed using multivariate logistic-regression. The effect of season of recruitment on and changes in serum 25(OH)D will be evaluated using multivariate analysis of covariance (ANCOVA) with two-tailed p-values less than values 0.05 representing statistical significance. Time to hypercalciuria or time to stone formation c will be analysed using a survival analysis technique and comparison of the 2 groups using a log-rank test.