Seasonal variation in urinary excretion of cyclic AMP in healthy people.

In a group of healthy young men and women the daily urinary excretion of cyclic adenosine 3', 5'-monophosphate (cAMP), calcium, hydroxyproline and the renal threshold phosphate concentration were evaluated at monthly intervals during 1 yr. A significant seasonal variation in cAMP urinary excretion was demonstrated, with a maximum occurring in spring and a minimum in winter. A clear annual rhythm was also observed when the other above parameters were considered. These findings are of importance in the interpretation of urinary cAMP values in clinical situations, and in the study of bone metabolism.