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Epinephrine-induced alterations in urinary cyclic AMP in hyper- and hypothyroidism
The Journal of Clinical Endocrinology and Metabolism
|October 1, 1975
Summary
Thyroid hormones affect cyclic AMP (cAMP) production. While hyperthyroidism doesn't increase overall cAMP, it enhances the response to epinephrine, suggesting altered cAMP systems.
Area of Science:
- Endocrinology
- Metabolism
- Molecular Biology
Background:
- Urinary cyclic AMP (cAMP) to creatinine ratios are often elevated in hyperthyroidism.
- The underlying mechanisms for this elevation require further investigation.
Purpose of the Study:
- To investigate the relationship between thyroid status and urinary cyclic AMP (cAMP) production.
- To assess the impact of thyroid hormone levels on the body's response to epinephrine stimulation.
Main Methods:
- Measured 24-hour urinary cAMP excretion in hyperthyroid, euthyroid, and hypothyroid subjects.
- Administered epinephrine infusions to assess cAMP excretion and cardiovascular response.
- Analyzed urinary cAMP and creatinine levels.
Main Results:
- Elevated urinary cAMP/creatinine ratios in hyperthyroidism are due to decreased creatinine excretion, not increased cAMP production.
- Hyperthyroid subjects showed a slight increase in 24-hour urinary cAMP excretion when ambulating.
- Epinephrine infusion significantly increased urinary cAMP excretion in hyperthyroid subjects more than in euthyroid subjects.
- Hypothyroid subjects showed no significant rise in cAMP excretion post-epinephrine.
- Cardiovascular response to epinephrine was heightened in hyperthyroidism and blunted in hypothyroidism.
Conclusions:
- Thyroid hormone levels significantly influence the adenylate cyclase-cyclic AMP generating systems.
- Altered thyroid states impact the body's response to stimuli like epinephrine.
- These findings suggest a role for thyroid hormones in modulating cAMP-mediated signaling pathways.