Effect of growth hormone therapy in growth hormone-deficient children on cytochrome P-450-dependent 3-N-demethylation of caffeine as measured by the caffeine 13CO2 breath test.

In 6 growth hormone-deficient children, we have demonstrated that 3-N-demethylation of caffeine as measured by the 13CO2 caffeine breath test is decreased following 1 month of growth hormone therapy (8.4 +/- 1.0 vs. 6.8 +/- 1.2% 13C/2 h after treatment). These findings could be of clinical importance. The initiation of growth hormone therapy in growth hormone-deficient children could alter the clearance of drugs metabolized through the mixed-function oxidase pathway given for concurrent conditions, and necessitate adjustment of the therapeutic regimen.