Procalcitonin
Procalcitonin (PCT) is a precursor of the hormone calcitonin, which is involved with calcium homeostasis, and is produced by the C-cells of the thyroid gland. It is there that procalcitonin is cleaved into calcitonin, katacalcin and a protein residue. It is not released into the blood stream of healthy individuals. With the derangements that a severe infection with an associated systemic response brings, the blood levels of procalcitonin may rise to 100 ng/ml. In blood serum, procalcitonin has a half-life of 25 to 30 hours.
Uses
Diagnosis and prognosis of sepsis
Measurement of procalcitonin can be used as a marker of severe sepsis and generally grades well with the degree of sepsis,[1] although levels of procalcitonin in the blood are very low. PCT has the greatest sensitivity (85%) and specificity (91%) for differentiating patients with SIRS from those with sepsis, when compared with IL-2, IL-6, IL-8, CRP and TNF-alpha.[2] However, the test is not routinely used and has yet to gain widespread acceptance.
In a comprehensive Meta-Analysis in 2007 the diagnostic accuracy of procalcitonin as a marker to differentiate sepsis from other non-infectious causes of systemic inflammatory responses was estimated including 18 studies (14 phase 2 and 4 phase 3 studies). [3] In this review the overall diagnostic performance of procalcitonin was low. The authors concluded that procalcitonin cannot reliably differentiate sepsis from other non-infectious causes of systemic inflammatory response syndrome in critically ill adult patients and should not be used as often as it is currently done in the critical care setting.
Diagnosis of bacteremia
A meta-analysis reported a sensitivity of 76% and specificity of 70%.[4]
Prognosis of pneumonia
A cluster randomized trial found that the procalcitonin level can help guide antibiotic therapy. In this trial, "on the basis of serum procalcitonin concentrations, use of antibiotics was more or less discouraged (<0.1 microg/L or <0.25 microg/L) or encouraged (> or =0.5 microg/L or > or =0.25 microg/L), respectively".[5]. However, a nonrandomized, observational study reported "limited, prognostic value" of the procalcitonin[6].
References
- ↑ Meisner M, Tschaikowsky K, Palmaers T, Schmidt J (1999). "Comparison of procalcitonin (PCT) and C-reactive protein (CRP) plasma concentrations at different SOFA scores during the course of sepsis and MODS" 3 (1): 45-50. PMID 11056723. [e]
- ↑ BalcI C, Sungurtekin H, Gürses E, Sungurtekin U, Kaptanoglu B (2003). "Usefulness of procalcitonin for diagnosis of sepsis in the intensive care unit". Critical care (London, England) 7 (1): 85-90. PMID 12617745. [e]
- ↑ Tang BM, Eslick GD, Craig JC, McLean AS (2007). "Accuracy of procalcitonin for sepsis diagnosis in critically ill patients: systematic review and meta-analysis". The Lancet infectious diseases 7 (3): 210-7. DOI:10.1016/S1473-3099(07)70052-X. PMID 17317602. Research Blogging.
- ↑ Jones AE, Fiechtl JF, Brown MD, Ballew JJ, Kline JA (2007). "Procalcitonin test in the diagnosis of bacteremia: a meta-analysis". Annals of emergency medicine 50 (1): 34-41. DOI:10.1016/j.annemergmed.2006.10.020. PMID 17161501. Research Blogging.
- ↑ Christ-Crain M, Jaccard-Stolz D, Bingisser R, Gencay MM, Huber PR, Tamm M, Müller B (2004). "Effect of procalcitonin-guided treatment on antibiotic use and outcome in lower respiratory tract infections: cluster-randomised, single-blinded intervention trial". Lancet 363 (9409): 600-7. DOI:10.1016/S0140-6736(04)15591-8. PMID 14987884. Research Blogging.
- ↑ Brunkhorst FM, Al-Nawas B, Krummenauer F, Forycki ZF, Shah PM (2002). "Procalcitonin, C-reactive protein and APACHE II score for risk evaluation in patients with severe pneumonia". Clin. Microbiol. Infect. 8 (2): 93-100. PMID 11952722. [e]
External link
- Procalcitonin - web site of the manufacturer of the PCT assay.