The loss of circadian rhythmicity of urinary solute excretion in idiopathic stone formers.

Circadian rhythmicity in urinary volume and excretion of creatinine, calcium, oxalate, uric acid and phosphate was studied in 15 idiopathic stone formers and in 17 control subjects who were age-matched, related adult males, living in the same house and engaged in similar occupations to those of the stone patients, but who had no clinically obvious stone disease. Three-hourly urine samples were collected and creatinine, calcium, oxalate, uric acid and inorganic phosphate were estimated. The time series of data were analysed by cosinor rhythmometry. Circadian rhythmicity has been described in urinary volume and urinary excretion of creatinine, calcium, oxalate, uric acid and inorganic phosphate in normal subjects, but it was not detected in the stone formers. The control subjects exhibited a circadian rhythmicity only in urinary volume and creatinine excretion. Thus they occupied a position midway between healthy adults, who exhibit circadian rhythmicity in all of the above parameters, and the stone formers, who appear to have lost it altogether.