Increased serum TSH response to TRH in cystic fibrosis.

The aim of the present study is to reassess the peripheral pattern 
of thyroid function in subjects with cystic fibrosis with special reference 
to their responsiveness to thyrotropin-releasing hormone (TRH) stimulation. In all the 
CF patients the basal levels of serum T4, T3, and TBG 
were within the normal range. Mean values in CF patients and 
in control children were not significantly different. In CF patients there 
is no correlation between the TSH response area and the basal 
level of serum T4, or with grading according to Shwachman and 
Kulczycki. We found no relation with therapy. In basal conditions, our 
data show a completely normal pattern of the serum concentration of 
T4, T3, TBG and TSH in subjects with CF in absence 
of iodide therapy. Thyroid status should be examined in patients with 
CF specially when they receive iodide therapy or other drugs which 
can enhance the impairment of thyroid function. 