Circadian periodicity of urinary inhibitor of calcium oxalate crystallization in healthy Indians and renal stone formers.

The inhibitory activity (IA) of calcium oxalate crystallization was investigated in healthy Indians and renal stone formers. A marked circadian rhythm was observed in men and women of both groups. The rhythm pattern was similar on the basis of sex; however, it was different in stone formers as compared to normals. The acrophase for crystallization of calcium oxalate was observed, respectively, at 05.43 and 05.52 h in healthy men and women, and at 09.52 and 09.23 h in male and female renal stone formers. Moreover, the acrophase of percent inhibition by IA was observed at 17.44 and 17.52 h in healthy participants and at 21.52 and 21.27 h in male and female stone formers, respectively. Therefore, the acrophase suggests a highest risk of crystallization during the morning hours and a minimum one during the evening hours. The day-night rhythmic pattern of urinary calcium, magnesium and phosphorus is discussed in relation to the rhythm of IA.