The saccharin test measures nasal mucociliary clearance. It is simple to perform, inexpensive, reproducible and is a screening test for the diagnosis of primary ciliary dyskinesia. Study objective - To establish the normal range of the ST in a group of presumed normal Brazilian children, and compare the results with those from the literature. Setting - The study was conducted in 2 schools in São Paulo, Brazil. Participants - Two hundred and thirty eight schoolchildren, 134 boys and 104 girls, age range 10.8-16.8 years, were studied. Information on respiratory diseases and smoking habits of parents were obtained from a questionnaire completed by the parents. Results - The questionnaires were analyzed and the children were then divided into 5 groups.The mean ST value in the group of normal children was 7.5 ± 2.8 minutes, comparable to the literature. The mean ST value in children with parental smoking, upper respiratory tract infection (URTI) within the preceding week, or allergy and URTI was not significantly different from the normal group. However, there was a significant difference between the normal group and those with allergy. As the standard deviation was greater in the groups with URTI, the population was reorganized into 2 groups, the criteria being the presence or not of URTI within the preceding week. Again, the mean ST values were not significantly different, but the variability was significantly different in the group with URTI. In 99% of the children studied the test took less than 30 minutes. Conclusions - Saccharin test values over 30 minutes should be considered abnormal and retested. We recommend that the test should not be performed during or within one month following an URTI.

Keywords: Saccharin test. Nasal mucociliary clearance.