Pancreas transplantation is currently the most reliable method for glycemic control in
insulin dependent diabetic patients. Outcomes of pancreas transplantation have improved
significantly over the years due to improved surgical techniques, medical management and
immunosuppression. However, weight gain after pancreas transplantation remains a common
problem with associated consequences such as development of type 2 diabetes, coronary
artery disease, graft loss, metabolic syndrome and increased risk of cardiovascular
death. Excessive weight gain is well known after liver and kidney transplantation;
however there are very few studies that have looked at weight gain after pancreas
transplantation. In a recent study by Knight et al, 26% of the pancreas transplant
recipients had excessive weight gain, defined as more than 30% of their baseline weight
by 1-year post transplant. The study focused mainly on the endocrine function of the
pancreas, explaining that excessive peripheral insulin circulation post-transplant may
explain the weight gain. Other factors like immunosuppression, increased oral intake and
potentially reduced activity may also have played a role. However no study has looked at
the possible role of exocrine secretion from the new pancreatic allograft, combined with
exocrine secretion of the old pancreas, leading to excessive availability of digestive
juices like trypsin, chymotrypsin, lipase, amylase, gelatinase, elastase etc. Our
hypothesis is that the excessive weight gain after pancreas transplant, which is more
than in other solid organ transplants, is driven by the excessive digestive juice leading
to improved conversion of available food and nutrient into storable energy and
subsequently leading to weight gain. The patient will therefore need to either increase
physical activity to avoid weight gain post-transplant or significantly reduce caloric
intake.
Fecal elastase test (FE-1)-elastase is a proteolytic enzyme produced by pancreatic acinar
cells. They bind to bile salt and pass through the gut without degradation. These levels
correlate well with the other pancreatic enzyme levels. Fecal elastase concentration
(FEC) has been used routinely to screen for pancreatic exocrine insufficiency (PEI).
Exocrine pancreatic juice has been a target for the management of obesity lately, with
the use of drugs like Orlistat (Xenical) that inhibits pancreatic lipase and therefore
interfere with the absorption of fat. If our theory of excessive pancreatic juice
availability after pancreas transplant can be proven, it can help guide the targeted use
and appropriate dosing of such drugs based on the level of the pancreatic juice as
measured by the FEC.