cAMP
Cyclic AMP (cAMP, cyclic adenosine 3',5'-monophosphate) serves as a regulatory molecule in all animal and many microbial cells. It is the "second messenger" for a number of peptide and catecholamine hormones which act on the cell surface. Hormones which act via cAMP include epinephrine, active in a number of tissues, glucagon, active primarily in the liver, adrenocorticotropic hormone (ACTH) in the adrenal cortex, thyroid stimulating hormone (TSH) in the thyroid, and parathyroid hormone (PTH) in osteoblasts and renal tubules. cAMP is determined mainly for the determination of abnormalities in hormone-related calcium and phosphate metabolism.