Sensitive pepsin immunoassay for detection of laryngopharyngeal reflux.
OBJECTIVE
To determine whether measurement of pepsin in throat sputum by immunoassay could be used as a sensitive and reliable method for detecting laryngopharyngeal reflux (LPR) compared with 24-hour double-probe (esophageal and pharyngeal) pH monitoring.


METHODS
Patients with clinical LPR undergoing pH monitoring provided throat sputum samples during the reflux-testing period for pepsin measurement using enzyme-linked immunoadsorbent assay.


RESULTS
Pepsin assay results from 63 throat sputum samples obtained from 23 study subjects were compared with their pH monitoring data. Twenty-two percent (14/63) of the sputum samples correlated the presence of pepsin with LPR (pH < or = 4 at the pharyngeal probe), of which the median concentration of pepsin was 0.18 microg/mL (range 0.003-22 microg/mL). Seventy-eight percent (49/63) of the samples unassociated with (pharyngeal) reflux contained no detectible pepsin. Mean pH values for pepsin-positive samples were significantly lower than negative samples at both esophageal probe (pH 2.2 vs. pH 5.0) (P < .01) and the pharyngeal probe (pH 4.4 vs. pH 5.8) (P < .01). When the pepsin assay results were compared with the pharyngeal pH data for detecting reflux (events pH < or = 4), the pepsin immunoassay was 100% sensitive and 89% specific for LPR.


CONCLUSIONS
Detection of pepsin in throat sputum by immunoassay appears to provide a sensitive, noninvasive method to detect LPR.
Knight
John
J
Center for Voice and Swallowing Disorders, Department of Otolaryngology, Wake Forest University Health Sciences, Winston-Salem, NC 27157, U.S.A.
Lively
Mark O
MO
Johnston
Nikki
N
Dettmar
Peter W
PW
Koufman
Jamie A
JA
D000136:Acid-Base Equilibrium / Q000502:physiology; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D015331:Cohort Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005745:Gastric Acidity Determination; D005750:Gastric Juice / Q000378:metabolism*; D005764:Gastroesophageal Reflux / Q000175:diagnosis*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007827:Laryngitis / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods; D010434:Pepsin A / Q000032:analysis / Q000378:metabolism*; D011336:Probability; D011446:Prospective Studies; D011863:Radioimmunoassay; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index
D010434:Pepsin A