Circadian study on serum gastrin in patients with duodenal ulcers and in a control group.

Two groups of subjects (one consisting of fourteen apparently healthy subjects, the other of fourteen patients with peptic ulcers) were kept for a least 7 days on the same living schedule (nocturnal sleep for 22(00) to 05(00) and meals standardized at 08(00)-08(30), 12(00)-12(30), 17(30)-18(00)). During 24 hors, samples of venous blood were obtained from each subject every 4 hours for the serum gastrin radioimmunoassay. The results were analyzed by mean cosinor method. The control group has a statistically significant circadian rhythm, while we were not able to detect a circadian rhythm in the patients with duodenal ulcers. The daily mean of serum gastrin levels appears to be significantly reduced in the ulcer group.