The effect of pyloromyotomy on serum and luminal gastrin in infants with hypertrophic pyloric stenosis.

Previous studies of the pathogenesis of congenital hypertrophic pyloric stenosis (CHPS) have implicated immunoreactive gastrin, although no consistent relationship has been demonstrated. In this study we have examined the effect which pyloromyotomy has on serum and luminal gastrin concentration after a mechanical and protein stimulus. Seventeen infants were examined preoperatively, and 1 week after pyloromyotomy. On each occasion, samples of serum and gastric contents were collected from fasting infants. Sixty cubic centimeters of water was placed into the stomach and further samples collected 20 min later. The water was then aspirated and replaced by 60 cc of 10% peptone broth and a third set of samples collected after 20 min. All samples from each patient were analyzed for immunoreactive gastrin in the same assay. Pyloromyotomy did not alter fasting serum gastrin (119.3 pg 2 11.9 preop vs 164.7 f 29.9 postop) nor did it alter the gastrin response to water. Pyloromyotomy decreased the incremental serum gastrin response to peptone broth (66.6 + 16.9 preop vs 18.9 + 11.7 postop). Luminal gastrin concentration was not significantly affected by pyloromyotomy. When the preand postoperative serum gastrin increments for water and peptone were plotted against the fasting gastrin levels, an inverse relationship was apparent which was statistically significant by regression analysis. Seen in this way, intragastric water and peptone have a dual effect on serum gastrin; a rise if the fasting serum gastrin concentration is low; a fall or lesser rise if the fasting serum gastrin concentration is high. The data suggest that the direction and magnitude of serum gastrin response to intragastric water or peptone is set by the fasting level, and is independent of pyloromyotomy.