Few elastase in the stool

Question

Hello,
In my son (4 years old), very few elastase could be found in the stool and four sweat tests had already been done (in two different CF-centers), all positive.
On the other hand, the genetic testing was negative.
Can it be that he has "only" problems with the pancreas?
The physicians do different test to him for two years, however a diagnosis could not be made, yet.
Many thanks for your answer

Answer

Hello,
You report, that a markedly reduced pancreatic elastase could be found in the stool of your 4-year-old son and that altogether four sweat tests, that have been performed in two different centers, had shown a positive result for CF.
On the other hand the genetic testing had been negative.
The following can be said on this situation.
If we presume that the sweat tests have been performed technically correct, and all results have been closely together in an area that is typical for CF, over 60 mmol/l chloride concentration, and additionally via the decreased pancreatic elastase a pancreatic insufficiency had been diagnosed, the criteria for an underlying CF are fullfilled. With the primarly common molecular genetic investigation (genetic test with a search for 29 or 36 of the most common mutations) just the tested mutations can be found respectively excluded. It could therefore well be possible, that your son has a combination of so-called more seldom mutations. The negative result of such a genetic testing does not exclude CF. In case your treating physicians (we presume that you are followed with your son at a CF-center) still have doubts about the diagnosis, it should either a broader molecular genetic investigation (complete sequencing of the gene) or a nasal potential difference measurement (NPD) be done to your son.
In general however it has to be said, that on the basis of the current available results, the diagnosis of CF has already been verified.
Yours sincerely,
Dr. H.-G. Posselt

17.02.2014