Comparison of 24-hour urinary citrate excretion in stone formers and healthy volunteers.

Low urinary citrate excretion is a risk factor in stone formers (SF). This study aimed to measure the urinary citrate excretion in SF and healthy volunteers at our center from 12 June 2008 to 20 August 2009. There were 28 SF patients (18 males and ten females) and 27 (18 males and nine females) age-matched healthy adult volunteers who participated in this study. Both groups had a similar living environment, extrinsic factors, diet and genetic descent. After collecting 24-h urine, citrate was measured using an enzymatic kit. Routine urinalysis and 24-h creatinine and uric acid were also performed. There was a significant difference in urinary citrate excretion level among SF (mean 310, SD 260 mg/L) and normal volunteer subjects (mean 800, SD 300 mg/L). By applying the previously defined normal values (320 mg/24 h) of urinary citrate in the local population, 43% of the SF in our study group was hypocitric, and none among the controls. We conclude that prevalence of hypocitraturia in stone formers was higher than that in healthy volunteers in our population.