Urinary excretion of adenosine 3',5'-monophosphate and guanosine 3',5'-monophosphate in normal children and those with cystic fibrosis.

The urinary excretion of adenosine 3',5'-monophosphate (cyclic AMP) and guanosine 3',5'-monophosphate (cyclic GMP) was examined in 98 normal children and 46 children with cystic fibrosis between the ages of 9 months and 18 yr. Diurnal variations in cyclic AMP and cyclic GMP excretion were observed in subjects from either group, and peak levels of cyclic nucleotide excretion were generally observed during the period of 0700 to 2100 h. Excretion rates (mumol/day) of cyclic AMP and cyclic GMP increased significantly with age. When cyclic AMP and cyclic GMP excretion rates were normalized for urinary creatine, or body weight, the values declined significantly with age in both groups of patients. Cyclic GMP excretion normalized for body surface area also decreased with age, while the value for cyclic AMP (2.86 plus or minus 0.08 mumol/day/m2, mean plus or minus SE) was constant with age in both normals and cystic fibrosis children. With some comparisons of age groups there were significant differences in cyclic nucleotide excretion between normal subjects and children with cystic fibrosis. The differences noted were dependent upon the methods used to normalize excretion rates (urinary creatine, body weight, surface area, and the ratio of cyclic AMP to cyclic GMP excreated). In general patients with cystic fibrosis excreted greater amounts of cyclic GMP than did normals. The most striking comparison was the ratio of cyclic AMP to cyclic GMP excreted which was 9.09 plus or minus 0.50 in all normal children and 4.41 plus or minus 0.32 in children with cystic fibrosis (P smaller than 0.001).