When do we use inflammatory markers? What do they tell us? Learn how these lab values make a difference in your clinical decision making!

This episode was written by pediatricians Lidia Park and Tammy Yau as well as pediatrics resident Anjali Doshi, with content support from Natasha Nakra, pediatric infectious disease physician. Pediatricians Tammy and Lidia take full responsibility for any errors or misinformation.

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Key Points:

• ESR is a marker of inflammation anywhere in the body. It is non-specific and doesn’t always indicate infection.
• CRP is an acute phase reactant that can be useful in inflammation or infection, but is also non-specific. This can be useful in trending if an infectious process or inflammation is improving.
• Recent studies now show that procalcitonin is a non-specific marker for bacterial infections and more clinicians are leaning away from using this marker.
• It is important before ordering these markers to assess which is needed and if a normal or elevated level will change your clinical plan before ordering unnecessary tests.

References:

Pihl AF, Balamuth F, Michelson KA. Inflammatory markers in pediatrics. Pediatr Rev. 2025;46(4):231-245. doi:10.1542/pir.2023-006920

Bell SG, Goldman RD. Pediatric Sepsis. In: StatPearls. StatPearls Publishing; updated January 2025. Accessed June 27, 2026. https://www.ncbi.nlm.nih.gov/books/NBK557485/

Shah S, Bachur R. Pediatric Dehydration. In: StatPearls. StatPearls Publishing; updated 2025. Accessed June 27, 2026. https://www.ncbi.nlm.nih.gov/books/NBK441843/

Shane AL, Sánchez PJ, Stoll BJ. Neonatal Sepsis. In: StatPearls. StatPearls Publishing; updated 2025. Accessed June 27, 2026. https://www.ncbi.nlm.nih.gov/books/NBK539794/

Yo CH, Hsieh PS, Lee SH, et al. Comparison of the test characteristics of procalcitonin to C-reactive protein and leukocytosis for the detection of serious bacterial infections in children presenting with fever without source: a systematic review and meta-analysis. Ann Emerg Med. 2012;60(5):591-600. https://pmc.ncbi.nlm.nih.gov/articles/PMC7640940/

Woods CR, et al. Clinical practice guideline for the evaluation and management of well-appearing febrile infants 8 to 60 days of age. Clin Infect Dis. 2020;70(3):538-543. doi:10.1093/cid/ciz635

Stockmann C, Ampofo K, Killpack J, et al. Procalcitonin accurately identifies hospitalized children with low risk of bacterial community-acquired pneumonia. J Pediatric Infect Dis Soc. 2018;7(1):46-53. doi:10.1093/jpids/pix018