Nasal nitric oxide for early diagnosis of primary ciliary dyskinesia: practical issues in children.

BACKGROUND: Primary ciliary dyskinesia (PCD) is a genetic disease characterized by abnormally beating cilia. In these patients, levels of nasal nitric oxide (nNO) are lower than those observed in healthy subjects. OBJECTIVES: We identify the nNO levels in healthy pre-school uncooperative children and in PCD patients, in order the application of nNO measurement in the early identification of young children with PCD. METHODS: We measured nNO in 77 healthy children (50 uncooperative and 27 cooperative) and in 10 PCD patients. Fifteen cooperative healthy children were also asked to perform an uncooperative test. RESULTS: PCD patients presented low nNO levels (29.7+/-5.7 ppb) compared to those observed in healthy children (358.8+/-35.2 ppb; p<0.05). nNO levels were increased in healthy cooperative children (650+/-60.6 ppb; p<0.05) as compared to those uncooperative aging more than 6 month (309.1+/-45.9 ppb; p<0.05) or less (128.1+/-16.2 ppb; p<0.05). Twenty-four uncooperative children with nNO values < or = 200 ppb performed a second evaluation at least 6 months later and mean levels increased from 104.7+/-10.5 ppb to 169.9+/-19.6 ppb (p<0.05). In the 15 collaborative children nNO levels were higher during the breath holding manoeuvre (687.7+/-96.9 ppb) than during the tidal breathing manoeuvre (335.9+/-57.9 ppb; p