The identification and measurement of uropepsin, a substance found in the urine which is thought to be identical with pepsinogen, has prompted the idea that uropepsin determinations may be a simple and accurate index of gastric secretory activity.
Available evidence indicates that pepsinogen present in gastric glands is secreted by two routes: directly into the lumen of the stomach, where it is converted to pepsin, and into the blood stream, whereby it is carried to the kidneys and excreted as uropepsin.*
Gray and co-workers have demonstrated the importance of the hypothalamic-pituitaryadrenal axis in the control of uropepsin excretion.† Administration of corticotropin (ACTH), cortisone, or hydrocortisone (Compound F) to patients produces an average increase in uropepsin excretion of almost 200%, paralleled by an equal increase in gastric pepsin and HCl output. That this increase is mediated by the adrenals is shown by the fact that patients with Addison's disease have very