Comparison of 24 hours urinary citrate levels in urolithiasis patients and healthy controls.

OBJECTIVE To identify the difference in urinary citrate excretion between Stone Formers (SF) and Healthy Volunteers (HV) as a metabolic risk factor, that predisposes to urinary stone formation and to compare levels of urinary citrate in (HV) with reference values. METHODS The 24 hours urinary citrate was evaluated in 40 patients treated for renal citrate and declared stone free, and 40 age matched healthy adults taken as controls. Both the groups had a similar living environment, extrinsic factors, diet and similar genetic descent. RESULTS There was no significant difference in urinary citrate excretion level among stone formers (mean 262 SD 197) and normal volunteer subjects (mean 269 SD 140). Using the previously defined normal values (200) of urinary citrate in the local population, 55% of stone patients in our study group were hypocitric. While using the same value, 45% of our normal volunteers were also hypocitric. If 320 was taken as normal limit, 70% of the patient's population and 72% of controls were hypocitric. The prevalence of hypocitraturia was similar in the age matched adult groups. CONCLUSION Certain intrinsic factors in our local subjects may account for the high prevalence of urolithiasis than in western population. Although the urinary citrate excretion of stone patients is similar to normal volunteers, uniformly low urinary citrate excretion may be a feature as a nation and not a predisposing factor for the lithogenesis. This supports the view that there may be more often prominent influences in stone formers possibly of genetic origin.