A Path Analysis To Investigate The Interaction Between Serum, Urinary And Demographic Factors Influencing Urine Calcium In Kidney Stone Formers

Abstract

Background: Hypercalciuria is one of the most important urinary risk factors in kidney stone formers. This study aimed to delineate the interaction of some demographic, serum, and urinary risk factors influencing 24-hour urinary (24-U) calcium excretion.Methods: This study was secondary data analysis, using data from 593 kidney stone patients referred to the Labbafinejad kidney stone prevention clinic from March 2015 to May 2019. The study considered serum, urinary and demographic factors that interact to influence 24-U calcium using path analysis.Results: The results showed that age and weight had an indirect effect on 24-U calcium. Among serum variables, PTH and creatinine had a significant direct effect on 24-U calcium. In comparison, 25-hydroxy vitamin D (25(OH)D) and phosphorus appeared to influence 24-U calcium through serum parathormone. Regarding 24-U metabolites, 24-U sodium, 24-U Urea, and 24-U citrate had a significant direct effect on 24-U calcium. Moreover, 24-U creatinine has a significant direct and indirect effect on 24-U calcium through 24-U citrate and 24-U Urea as mediating variables. 24-U citrate had the most effect on 24-U calcium, following 24-U creatinine, 24-U Urea, 24-U sodium, serum creatinine, and weight.Conclusion: Except for serum calcium, all other predictors had direct and/or indirect effects on 24-U calcium. Serum 25(OH)D had a negligible indirect effect on 24-U calcium. Controlling dietary intake of protein and sodium and bodyweight seems very important in kidney stone formers with hypercalciuria.