[Effect of synthetic secretin and GIH-cholecystokinin on serum gastrin levels].

In response to the report of a false-positive increase in serum gastrin with the use of natural secretin (Boots), 11 test persons were enlisted in order to examine the effect of a new synthetic secretin (Hoechst), both alone and in combination with natural CCK, on serum gastrin concentration. 6 of the test persons were subjected to a randomised cross-over study under NaCl infusion. Under secretin (0 to 60 minutes) there was a significant fall in gastrin from 32 +/- 2.3 pg/ml to 23 +/- 2 pg/ml (p less than 0.01). When CCK was also administered (60 to 120 minutes) the gastrin level increased to 46 +/- 3.5 pg/ml (75 versus 0 minutes: p less than 0.01), 75 versus 60 minutes: p less than 0.001). At the end of the infusion the gastrin level had fallen significantly once more to 21 +/- 2 pg/ml (135 versus 120 minutes: p less than 0.001, 135 versus 0 minutes: p less than 0.01). On the basis of in vitro studies -- which revealed a cross-reaction of 2.4% - the increase in gastrin under CCK is not regarded as being due to cross-reaction with CCK but rather to contamination by other peptides.