Urinary and blood levels of adenosine 3',5'-monophosphate, phosphorus and calcium in infants.

The changes during the first year of life in urinary and nephrogenous cAMP levels were determined in 152 normal, full-term infants using spot urine samples. The use of spot tests simplifies considerably the logistics of the cAMP determination which can be used for the investigation of parathyroid function. Levels of urinary and nephrogenous cAMP (expressed both as a function of creatinine excretion as well as glomerular filtration rate) rose from birth to 1 year of age, whereas plasma cAMP levels did not change significantly. Levels of cAMP (both urinary and nephrogenous) were significantly correlated with age, length, weight, and urinary phosphorus concentrations of the infants. No significant correlation could be observed, however, between serum phosphorus or serum and urinary calcium on the one hand, and urinary or nephrogenous cAMP on the other.