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# NIH Respiratory Tract Marker Study
- URL: https://www.fdaweb.com/nih-respiratory-tract-marker-study/
- Published: 2018-02-14T12:00:00.000Z
- Updated: 2026-09-14T23:22:22.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5140765

The National Institute of Allergy and Infectious Diseases says it is sponsoring a clinical trial to determine whether low blood levels of the protein procalcitonin (PCT) can reliably indicate whether a person’s lower respiratory tract infection will improve with antibiotic treatment. The agency [says](https://www.nih.gov/news-events/news-releases/nih-study-will-assess-biomarker-potential-indicator-whether-lower-respiratory-tract-infections-improve-antibacterial-treatment?ref=fdaweb.com) that healthcare providers often prescribe a course of antibiotics as standard treatment without knowing for certain whether an infection is bacterial or viral.

Procalcitonin is normally produced by a healthy body in minute quantities, and serves as a precursor to calcitonin, a hormone that helps regulate calcium levels. Researchers doing the study theorize that low PCT levels in patients with lower respiratory tract infections may indicate that the infection is viral and not bacterial.