Sensitive Pepsin Immunoassay for Detection of Laryngopharyngeal Reflux

Authors

  • John Knight PhD,

    1. Center for Voice and Swallowing Disorders, Department of Otolaryngology, Wake Forest University Health Sciences, Winston–Salem, North Carolina, U.S.A.
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  • Mark O. Lively PhD,

    1. Center for Voice and Swallowing Disorders, Department of Otolaryngology, Wake Forest University Health Sciences, Winston–Salem, North Carolina, U.S.A.
    2. Department of Biochemistry, Wake Forest University Health Sciences, Winston–Salem, North Carolina, U.S.A.
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  • Nikki Johnston PhD,

    1. Center for Voice and Swallowing Disorders, Department of Otolaryngology, Wake Forest University Health Sciences, Winston–Salem, North Carolina, U.S.A.
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  • Peter W. Dettmar PhD,

    1. Center for Voice and Swallowing Disorders, Department of Otolaryngology, Wake Forest University Health Sciences, Winston–Salem, North Carolina, U.S.A.
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  • Jamie A. Koufman MD

    Corresponding author
    1. Center for Voice and Swallowing Disorders, Department of Otolaryngology, Wake Forest University Health Sciences, Winston–Salem, North Carolina, U.S.A.
    • Dr. Jamie Koufman, Center for Voice and Swallowing Disorders of Wake Forest University, Medical Center Boulevard, Winston–Salem, NC 27157-1034, U.S.A.
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  • Funding for this study was provided by the Center for Voice and Swallowing Disorders

Abstract

Objectives/Hypothesis: 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.

Study Design: 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 ≤ 4 at the pharyngeal probe), of which the median concentration of pepsin was 0.18 μg/mL (range 0.003–22 μg/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 ≤ 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.

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