PP
Meaning of PP: A hormone that mostly tells the pancreas to stop, released once a meal is under way and rising as the body ages.
Definition of PP
PP is short for pancreatic polypeptide, a small protein hormone made by specialized cells in the islets of the pancreas. It acts mainly as a brake, reducing the output of digestive enzymes and the emptying of the gallbladder once a meal has been dealt with, and it contributes to the signals that register fullness after eating.
Where is it made and what triggers its release?
The islets scattered through the pancreas contain several kinds of hormone-producing cell. The best known make insulin and glucagon; a further population, concentrated in the head of the organ, makes pancreatic polypeptide. Release is prompted by eating and is driven largely by the vagus nerve, which carries signals from the brain to the gut, so the rise begins with the meal rather than waiting for digestion to finish. Protein in the meal is a particularly strong stimulus. Levels fall back over the following hours.
Why is it measured?
| Factor | Effect on the result |
|---|---|
| Recent eating | Raises the level, so the timing of the sample matters |
| Age | Levels tend to rise over the decades |
| Kidney impairment | Reduced clearance raises the level |
| Neuroendocrine tumors | Some pancreatic tumors secrete it in large amounts |
PP appears in the panel of gut hormone measurements ordered when a neuroendocrine tumor of the pancreas is suspected, since a tumor of the cells that make it produces a persistently high level. It also features in research on appetite regulation and in the assessment of nerve supply to the gut, because a blunted rise after a meal suggests the vagal pathway is not working. On its own the result means little, which is why a pancreatic function test is interpreted as part of a wider picture.
Does PP always mean pancreatic polypeptide?
No. The same two letters are used in clinical records for other things entirely, among them pulse pressure, the difference between the upper and lower blood pressure readings, and postprandial, meaning after a meal. In research writing PP commonly marks a per-protocol analysis. Nothing distinguishes them except context, so the surrounding text has to be read to know which is meant.
Also known as
Used in a sentence
PP levels were measured as part of the evaluation of the patient's pancreatic function.
Good to know
PP levels rise after eating and tend to increase with age, so the timing of the blood sample relative to food and the person's age are both relevant when a result is interpreted.