Sunday, July 15, 2012

The Amazing Pancreas

The pancreas is an amazing organ. It’s the unsung hero of the body. The body is rather like a team with each organ having its own specialised job to do: the heart pumps blood round the body, the lungs oxygenate the blood. But the pancreas is the utility player of the body, sitting quietly out of sight behind the big name organs, the stomach and liver. But there it carries out multiple functions key to the body’s survival. It’s not a one-trick-pony organ like some of its more illustrious teammates but a multi-skilled player deserving of far more credit than it receives.

The pancreas is responsible for supply and control of multiple hormones. Not just the all-important insulin but its partner in crime glucagon, as well as somatostatin and pancreatic polypeptide. On top of all this the pancreas produces many enzymes that help the body digest food: lipase, amylase, trypsinogen, chymotrypsinogen, elastase and carboxypeptidase. An impressive list for such an underestimated organ.

Of course all this makes living without a pancreas quite a challenge.

We have tried our best to replicate all the functions that nature perfected long ago but our attempts at being a pseudopancreas appear amateurish when compared to such an impressive organ.

The biochemists have given us the enzymes and drugs to help Finlay survive, modern medical technology has given us insulin pumps to finely tune our glucose control and the surgeons have aided us with 24-hour feeding access through a feeding tube. But it is one of the pancreases lesser-known functions that has left us struggling recently.

One of Finlay’s issues is his size. He is small. At 4 years old we can get him in 2 year old pants if we pull the elastic waistband really tight. Unfortunately fattening him up has not been easy. He grew reasonably well in the first couple of years but he has hardly put on any weight in the last year. And the problem seems to be an inability to digest and absorb his food. We can give him all the food and nutritional drink supplements we can shove in him. We can feed him through a tube when he’s asleep and we can give him lots of enzymes to replace the ones he can’t produce. But all this isn’t helping him grow. And it’s a clever little property of the pancreas that is to blame.

When food exits the stomach it is very acidic due to the gastric acid in the stomach. This creates a problem as the enzymes released by the pancreas to digest the food are destroyed by strong acid. So the pancreas releases bicarbonate (the same as baking soda) along with the enzymes to neutralise the acidic food and allow the enzymes to work.

So for our attempts at being a pseudopancreas we feed him some enzymes in tiny spheres that have a special coating that protects the enzymes through the acid stomach but which dissolve, releasing the enzymes, once they are in the less acidic duodenum. Unfortunately because he has no pancreas he has no bicarbonate released into his gut so the duodenum stays acidic. That means the little spheres carry on through the gut until eventually the environment is suitable for the coating to dissolve but by then most of the benefit has been lost and not enough food gets digested.

So what is the answer? With the rarity of Finlay’s condition there are no treatment guidelines, no established protocols backed by years of research and experience. We work on a combination of educated guesswork and…. well, complete guesswork. One strategy is to look at conditions with similar problems. In this case cystic fibrosis is a good model for what Finlay is dealing with. In CF the secretions from the pancreas can become blocked as the organs get covered in the thick gunk that typifies the disease. For many CF patients, reducing the stomach acid works well to reduce the acid environment in the duodenum and let the enzymes work.

So we have started a course of a proton pump inhibitor, a class of drug that reduces the amount of acid the stomach produces. Hopefully that will help reduce the acidity of the whole digestive tract and get more food being digested and absorbed.

Time will tell if this helps him put weight on but if it does it will be one more small victory in our efforts to replicate this amazing organ.

2 comments:

  1. How do you pick a dose of a PPI for a person that size?

    Are pancreatic enzymes necessary for digestion of sugars and proteins, or just fats?

    I have had pancreatitis (may still have some degree of pancreatitis) and I know that fat was my big bugbear, and that plain sugar was my most easily tolerated food.

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    1. The main problem is the fats which are digested by pancreatic lipases but the pancreas is also responsible for digesting proteins by trypsins and then amylases digest complex carbs. Amylase is also produced in saliva so there would be some starch (carb) digestion even without a functioning pancreas.
      Simple sugars like glucose don't need pancreatic enzymes which is a huge relief from the diabetes side. When we need to get glucose levels up the last thing we want to worry about is digestion! So it makes sense that you found sugar the easiest food to tolerate.
      I'm not sure how the doctor dosed for the PPI. Our son was on PPI when he was very young to alleviste some gastric reflux and he tolerated it well then and he's quite a bit bigger now so it should be OK.

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