Can the diagnose change?

Question

Hello,
in the year 2008, two sweat tests of my at that time 5-year-old daughter were 59 and 78. After this, there were two further sweat tests at a university hospital with the values 26 and 12. The measurement of the elastase in the stool was 638 and 629 as double measurement. Therefore the result was "negative" concerning the illness CF.
Actually she is ill for already 4 weeks and the antibiotic, the mucolytic and inhaling do not bring any relief.
Now my question: can the diagnosis "CF" be positive now?

Answer

Hello,
you report, that your daugher, when she was 5 years old, had 2 sweat tests in 2008 with increased values of 59 and 78 mmol/l and that then, at a control in a university hospital, normal values had been measured of 26 respectively 12 mmo/l. At the same time, the elastase I in the stool has been judged to be normal with values over 500, so that CF could be excluded.
As your daughter suffers now for 4 weeks from a longlasting infection of the airways and an antibiotic therapy as well as the intake of mucolytic drugs and inhalation have until now not shown any success, you ask, if the diagnose could have changed.
As CF is an inherited metabolic disease, the diagnose can not have changed. The last measured results could only have been false negative in the past. The measurement of the elastase I prove that your daughter has a normal function of the pancreas. This finding is with high probability reliably right, as this laboratory measurement is not complicated. It is known, that about 15% of CF patients have a normal pancreatic function lifelong. One could speculate now, that the last measured sweat tests have been false negative and that the first measured results have been right. As the last ones have been measured at a university Hospital - therefore seemingly at a specialized CF center - I would like to give more weight to them.
As in the last 2 months in Germany a real series of longlasting infections of the airways (mostly caused by viruses) has been observed in children and adults, I speculate, that your daughter is as well suffering from such an infection. Therefore one could still wait under supervision of a pediatrician spezialized in airway infections (pneumologist).
If doubts will still persist, further sweat tests would have to be done in a specialized laboratory.
We hope that your daughter will be doing better, soon.

Best regards,
Dr. H.-G. Posselt

13.10.2014