Gastrin secretion in the menstrual cycle and pregnancy.

: Gastrin (1--17) concentration was estimated under basal conditions in 12 menstruating women, and 42 women with normal pregnancy. In 10 women with normal pregnancy this hormone was also measured 10 days after delivery. In addition, gastrin was determined after stimulation with a standard protein meal in 7 menstruating women, 12 women with normal pregnancy and 14 women with complicated pregnancies. Umbilical vein blood levels of gastrin were also determined in 5 cases while, in 3 women serial hormone estimations were carried out for 24 hours after normal delivery. The mean (+/- SEM) basal gastrin concentration was 36.1 +/- 2.9 pg/ml in the productive and 45.4 +/- 2.0 in the secretory phase of the cycle (p less than 0.02). The mean basal concentration in normal pregnancy (60.4 +/- 5.4) was higher than that of the normal cycle as a whole (p less than 0.001), showed no significant variations related to the progress of pregnancy, and fell to normal cycle levels after delivery (42.1 +/- 2.9). In complicated pregnancies the mean hormone concentration (47.0 +/- 2.3) was lower than that of normal pregnancies (p less than 0.05) and similar to that of the secretory phase of the cycle. Gastrin responses to protein meal were similar in all 3 groups studied, with maximal concentration at 30 min, and a gradual decline thereafter. Umbilical vein blood levels of gastrin were generally higher than in maternal circulation but not significantly so. Serial estimations of gastrin after delivery failed to show any uniform pattern of changes. It is concluded that variations of gastrin secretion related to the phase of the menstrual cycle or the reproductive state may occur in women.