Pepsin measured in induced sputum--a test for pulmonary aspiration in children?
OBJECTIVE
The purpose of this study was to investigate if pepsin measured in sputum is a useful marker of pulmonary aspiration secondary to gastroesophageal reflux (GER) in children. It is possible that the induced sputum procedure could cause GER and invalidate the results. The hypothesis stated that healthy children (those without history of respiratory or gastroesophageal symptoms) would not have pepsin detected in induced sputum.


METHODS
Children attending surgical outpatients in the Royal Belfast Hospital for Sick Children (Belfast, Northern Ireland) were recruited. After spirometry, sputum was obtained by induction with hypertonic 3% saline. Spirometry was repeated, and complications were noted. An "in-house" enzyme-linked immunosorbent assay was used to measure pepsin concentration in sputum. The lower limit of detection of pepsin was 1.19 ng/mL.


RESULTS
Children (n = 21) aged 4 to 16 years were recruited. Twenty children completed the study. No adverse effects were reported. Pepsin was detected in 17 (85%) of 20 sputum samples.


CONCLUSIONS
The act of sputum induction appears to induce physiologic GER in a healthy childhood population. The analysis of pepsin in sputum obtained by sputum induction is therefore not useful in the investigation of reflux-related respiratory disease.
Ervine
Evelyn
E
Respiratory Research Group, Queen's University Belfast, Northern Ireland, UK. evelynervine@hotmail.com
McMaster
Cyril
C
McCallion
William
W
Shields
Michael D
MD
D000293:Adolescent; D000367:Age Factors; D015415:Biomarkers; D002648:Child; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D005764:Gastroesophageal Reflux / Q000150:complications* / Q000175:diagnosis / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D057230:Limit of Detection; D008297:Male; D009660:Northern Ireland; D010434:Pepsin A / Q000032:analysis*; D053120:Respiratory Aspiration / Q000175:diagnosis* / Q000209:etiology / Q000378:metabolism; D012307:Risk Factors; D012462:Saline Solution, Hypertonic / Q000008:administration & dosage / Q000494:pharmacology; D012463:Saliva / Q000737:chemistry*; D013147:Spirometry; D013183:Sputum / Q000737:chemistry* / Q000187:drug effects / Q000201:enzymology
D015415:Biomarkers; D012462:Saline Solution, Hypertonic; D010434:Pepsin A