We investigated the circadian rhythm of chromogranin A (CgA) concentrations in saliva and blood samples from 40 male college students collected at 7 : 00, 8 : 00, 10 : 30, 12 : 30, 17 : 30, and 22 : 30. CgA concentrations were determined by ELISA. Salivary CgA levels peaked upon awakening, and then quickly decreased to the nadir after 1 hour and maintained a low level throughout the day. On the other hand, plasma CgA did not show any obvious circadian rhythm. These findings suggest that salivary and plasma CgA has different routes of secretion.
2007 Biomedical Research Press