Urinary excretion of cyclic adenosine 3',5'-monophosphate in children of different ages.

The urinary excretion of cyclic AMP was investigated in 97 healthy children, 3 months to 16 years old. When the excretion was expressed as mumol/24 h an increase with age (r = 0.693, P less than 0.001) and an increase with body weight (r = 0.700, P less than 0.001) were found to be quite similar. In relation to surface area, the average excretion for children up to 91/2 years old was 4.45 +/- 1.71 mumol/m2 in constrast with 2.22 +/- 0.66 mumol/m2 in older children (P less than 0.001). The decline appears to be associated with approaching puberty. When cAMP excretion was related to urinary creatinine, an inverse correlation with age was found (r = -0.772, P less than 0.001). In the youngest category, 3 months to 4 years old, the ratio was 9.26 +/- 1.49 mumol/g creatinine vs 4.67 +/- 1.05 mumol/g creatinine in the age group 12 to 16 years old (P less than 0.001), which compares closely with the normal adult average of 4.34 +/- 1.25 mumol/g creatinine found in our previous study. Throughout there was no evidence of sex differentiation.