Sweat test

Question

My child is 5.5 years old and sweats too much while sleeping. I have to change clothes 5-6 times a night. I change his clothes and after 10 minutes he is soaking wet. That is why he has frequent coughing and sputum. He started sweating after the age of 3. Up to the age of 3 he had no medication, not even paracetamol.
Should we do a sweat test? I, his mother, am a CF carrier at 80% of mutations and his father is negative for CF mutations at 80%.

Answer

Dear friend,
Cystic fibrosis (CF) is a disease which is characterized by increased concentration of salt in the sweat.
Based on what you say your child presents an abonormality in the quantity of the sweat production and not in its composition. CF does not cause hyperhidrosis (increased sweat secretion). Your child, if it had CF, together with the presenting hyperhidrosis to such a great extent as you describe, would present dehydration as well.
Furthermore, CF is characterized by other symptoms, such as pulmonary infections, delayed growth and low weight, fatty, smelly feces, etc. You do not mention any such details.
Personally I believe that your child does not suffer from CF. You should counsel with your pediatrician and seek elsewhere the causes of the hyperhidrosis (hyperthyroidism, congenital heart disease, etc).
Yours friendly,
Dr. Stavros Doudounakis

17.12.2013