CF yes or no?

Question

Hello,
my 8-year-old daughter has health problems since birth (croup, bronchitis, pneumonia etc.).
She is 119cm tall and weighs 18.5 kg. Allergy tests, blood investigations, bronchoscopy, ciliar diagnostics, x-rays etc. have already been done.
She takes Viani 125® (fluticasone and salmeterol) for 3 years, however the infections stay and are treated with antibiotics (already 24 times), betamethasone orally and montelukast.
CF has been excluded.
Sweat test: 2007 NaCl 24 mmol/l
2011 osmolality 29 mmol/kg, chloride 7 mmol/l, collection volume 95.
I have read in the internet that one can suffer from CF in spite of a negative test.
What do you recommend?
Is there a possibility of CF?

Answer

Hello,
you report that your 8-year-old daughter presents with health problems since birth, that concentrate on the airways (croup-syndrome, bronchitis and pneumonias). Because of the seemingly massive problems, extensive diagnostic investigations have been performed with investigations of the blood, bronchoscopy, investigation of the ciliary function and x-rays.
For 3 years she has a long-term therapy with Viani 125®. Already 24 cycles of antibiotic therapy have been done due to recurrent infections. You report that CF has been excluded on the basis of several sweat tests (2007 NaCl 24 mmol/l, 2011 osmolality 49 mmol/Kg, chloride 7 mmol/l). Furthermore, you report that your daughter is 129cm tall and weighs 18.5 kg. You ask, if it could be possible that your daughter suffers from CF in spite of the negative sweat tests.
In gerenal it can be said on your question, that it is hardly imaginable that in case of the very marked pulmonary manifestation of your daughter CF with a negative sweat test is underlying. CF patients with a borderline to normal sweat test show in general a very mild course of the illness.
You report, that your daughter is 119cm tall and weighs 18.5 kg. Both values are in the lowest normal range for an 8-year-old girl, whereby the relation of height and weight is normal. Does your daughter fit in the family picture with her stature? Where applicable, has a pancreatic insufficiency been ruled out to exclude a failure to thrive?
The following has to be said on your daughter's sweat test diagnostics. According to international standards a pilocarpine ionotophoresis should be performed with measurement of the chloride value with a chloridometer. I would therefore suggest, to consult a CF-center, that performs this measurement routinely. There, a double measurement of the chloride value of the sweat of both arms should be performed. If those values would be normal, you can assume with certainty that CF can be excluded. Then, it should be looked for other reasons of the marked pulmonary illness (exclusion of chronic reflux, immunodeficiency etc.)
We wish you and your daughter much luck.
Yours sincerely,
Dr. H.-G. Posselt

26.09.2013