Abstract
BackgroundInduced sputum cell counts are a non-invasive, reliable method for evaluating the presence, type, and degree of inflammation in the airways of the lungs. Current reference values for induced sputum cell counts in healthy adults do not account for the effects of circadian rhythm, including diurnal variation. The objective of this study was to describe the diurnal variation in induced sputum cell counts, compared between early morning and late afternoon, in healthy adult individuals.Methods100 healthy adult subjects with no history of lung disease and normal bronchial reactivity proceeded with induced sputum testing at 7 am and 4 pm on different days. The order of testing was randomized. The cytotechnologist preparing and performing the cell counts was blinded to the sample collection time and subject characteristics.Results65 subjects were included in the final analyses. There was no significant change in the total and differential sputum cell counts between the 7 am and 4 pm collections. There was good inter-observer agreement with respect to differential sputum cell count interpretation.ConclusionsThis is the largest study to assess the variation in induced sputum cell counts in healthy adult subjects at different times of the day. We found no significant change in total and differential sputum cell counts between the 7 am and 4 pm collection time points. This is in contrast to studies in asthmatics that demonstrated a circadian variation in sputum cell counts and other markers of inflammation, suggesting that fluctuations in airway inflammatory cells during the day are a disease-specific effect.
Highlights
Induced sputum cell counts are a non-invasive, reliable method for evaluating the presence, type, and degree of inflammation in the airways of the lungs
It is necessary to understand the effect of normal circadian variation, including diurnal variation, on induced sputum cell counts in healthy non-asthmatic individuals, especially when testing for clinical or research purposes can be performed at various times throughout the day
Adult study participants were eligible for inclusion into the study, provided they had no history of any chronic respiratory conditions and had normal spirometry, with no significant bronchodilator response (FEV1 and Forced vital capacity (FVC)
Summary
Induced sputum cell counts are a non-invasive, reliable method for evaluating the presence, type, and degree of inflammation in the airways of the lungs. One small study examining the circadian changes in induced sputum in 11 asthmatic patients demonstrated an increase in early morning total sputum leukocytes and eosinophils [15]. Whether these changes are a normal response or specific to asthma remains to be determined. It is necessary to understand the effect of normal circadian variation, including diurnal variation, on induced sputum cell counts in healthy non-asthmatic individuals, especially when testing for clinical or research purposes can be performed at various times throughout the day. Similar to patients with asthma, total sputum leukocytes would be elevated in the early morning compared with the evening
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
