The effect of severe trauma on urinary cyclic AMP in children of different ages

Urinary excretion patterns of cyclic AMP and cyclic GMP following thermal injury

Measurement of 24-h urinary cyclic AMP and cyclic GMP levels in 19 patients for up to nine days after thermal injury has revealed differences in cyclic nucleotide excretion patterns between "severe" and "mild to moderate" groups of burned patients, classified according to a predictive index of burn mortality. Cyclic AMP excretion fell significantly from a high initial level in the "severe" group, but showed no significant change in the "mild to moderate" group. Differences in cyclic AMP excretion between the two groups of patients were only significant on the second day following burn injury. There was no correlation between cyclic AMP output averaged for each patient over the first nine days and percentage body surface area of the burn or the predictive index. In contrast to the results for cyclic AMP excretion, cyclic GMP output rose significantly over the 9-day period in severely burned patients, while levels reached a plateau on days four to six for the moderate to mild group. When cyclic GMP excretion was averaged over the first nine days for each patient, a significant correlation with both percent body surface area of burn and the predictive index of burn mortality was found. The tissue source or sources which are responsible for increased cyclic GMP excretion are as yet unknown.

Urinary cyclic AMP and post-traumatic acute renal failure

Consecutive daily urinary excretion of cyclic AMP has been investigated in 16 patients with severe trauma or illness, five of whom developed acute renal failure (ARF). Fluctuations in the nucleotide excretion exceeded the range found in 20 healthy volunteers (1.26-14.74, mean 7.13+/-1.18 vs. 2.04-10.10, mean 5.07+/-2.21 micronmol/24 h). This resulted in a 41% increase of cAMP excretion in the group with normal renal function (P less than 0.003) with the highest individual increase of 87%. The excretion usually reached its peak by 24 h after trauma and its lowest value by the third day, (first day vs. third day; 7.82+/-4.23 vs. 3.96+/-2.58 micronmol/24 h, P less than 0.05 for a group of 11 patients), while creatinine clearance remained normal. In four patients with severe ARF, the mean urine volume was above control value but the cAMP excretion was reduced to 3.9 to 14.4% and in one patient with a mild ARF to 60.6%. Creatinine excretion of the group was less reduced than that of cAMP (41.2% vs. 19.6%, resp.). cAMP excretion declined proportionally with diminishing creatinine clearance. In the category of 33-65 ml/min it decreased by 33.4% to 3.39 micronmol+/-1.16 micronmol/24 h. cAMP/creatinine ratio proved to be a less sensitive indicator than cAMP/24 h. Daily output of cAMP and creatinine correlated highly with diuresis in ARF patients, controls (always P less than 0.001) and less in patients with normal renal function (P less than 0.02). Urinary cAMP appears to be a very sensitive and early indicator of the onset of ARF and subsequent recovery. This warrants its further study.