Study of Circadian Rhythmicity of Urinary Excretion of Glycosaminoglycans in Normal Subjects and Stone Formers
Glycosaminoglycans (GAGs) are potent inhibitors of calcium-oxalate crystallization and/or crystal aggregation. The urinary concentration of GAGs has been shown to vary over a 24-h period (1). The aim of the present study was to investigate circadian rhythmicity in urinary GAGs concentration in healthy adults and to compare it with that of calcium-oxalate nephrolithiasis patients. Three-h urine samples were collected for 24 h beginning at 0000 h (midnight) from 33 healthy male adults and from 27 patients with calcium-oxalate nephrolithiasis. Urinary GAGs were colorimetrically assayed in terms of glucuronic acid content (1). The data were analyzed by single cosinor rhythmometry and population-mean-cosinor rhythmometry (2).