Target values for pancreatic elastase in case of CF

Question

Dear ladies and gentlemen,
I would like to ask a question. Probably you could help us?
Shortly about the background:
We are parents of a 2.5 year-old happy daughter with CF.
Our pediatrician (who is not part of our CF center team) directed the investigation of a stool sample of our daughter, after she listened to a talk of Prof. Ellemunter, that we also attended. She would like to have the value for the pancreatic elastase measured. We favour this very much, especially as gastro-intestinal investigations do not seem to belong to the standard investigations of our CF center, according to our impression.

Unfortuantely our pediatrician has not the target values that were reported by Prof. Ellemunter as to be the aim.
Could you help us in here further?
We would be very pleased about an answer.

Answer

Hello,
elastase is a highly specific enzyme for the pancreas that is not destroyed by other enzymes in the gut. The measurement of the pancreatic elastase in the stool shows the exocrine function of the organ independed from the enzyme intake. The exocrine function enables the digestion of fat via the release of enzymes and is also repsonsible for the bicarbonate secretion. The elastase value in the stool is in case of pancreatic sufficient patients over 200µg/g stool. In case of values below 100 µg/g stool the patients need oral pancreatic enzymes. As pancreatic sufficient patients could turn to be pancreatic insufficient in the course of time, a frequent measurement of the elastase is recommended.

In the stool of CF patients frequently other parameters are measured, as e.g. chymotrypsin and or calprotectin. Chymotrypsin is produced by the pancreatic cells as inactive chymotrypsinogen, that is released in the small bowel and is there transferred into the active form. Even if the activity of chymotrypsin is reduced quickly during the gut passage, there is a good correlation between the amount of chymotrypsin and the measurement of its acitivity in the stool. Therefore the measurement of chymotrypsin in the stool count to the indirect diagnostic methods of the exocrine pancreatic function. Orally taken pancreatic enzymes, however, are also measured with the commercial test kits for the chymotrypsin activity in the stool. Therefore the measurement of the chymotrypsin acitivity in the stool under enzyme substitution can only give information about the intake of enzymes/ compliance of the patient, however not about the function. There is no defined target value and it is not aimed.

The stool fat measurment gives information about the adjustment with enzymes, that is however only done at very few CF centers for understandable reasons.

Signs for the clinical success of a food adapted correct enzyme substitution are good thrive with weight and height along the 50th percentile as well as the absence of symptoms.

Best regards,
Dr. Helmut Ellemunter

14.01.2016