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, [Meisner M, Tschaikowsky K, Palmaers T, Schmidt J. Comparison of procalcitonin (PCT) and C-reactive protein (CRP) plasma concentrations at different SOFA scores during the course of sepsis and MODS. Crit Care. 1999;3(1):45-50. PMID 11056723 [http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=154110 Full Text] ] 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. [Balci C, Sungurtekin H, Gurses E, Sungurtekin U, Kaptanoglu B. Usefulness of procalcitonin for diagnosis of sepsis in the intensive care unit. Crit Care. 2003 Feb;7(1):85-90. Epub 2002 Oct 30. PMID 12617745 [http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=154110 Full Text] ] However, the test is not routinely used and has yet to gain widespread acceptance.Fact|date=January 2008

Diagnosis of bacteremia

A meta-analysis reported a sensitivity of 76% and specificity of 70%.cite journal |author=Jones AE, Fiechtl JF, Brown MD, Ballew JJ, Kline JA |title=Procalcitonin test in the diagnosis of bacteremia: a meta-analysis |journal=Annals of emergency medicine |volume=50 |issue=1 |pages=34–41 |year=2007 |pmid=17161501 |doi=10.1016/j.annemergmed.2006.10.020]

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".cite journal |author=Christ-Crain M, Jaccard-Stolz D, Bingisser R, Gencay MM, Huber PR, Tamm M, Müller B |title=Effect of procalcitonin-guided treatment on antibiotic use and outcome in lower respiratory tract infections: cluster-randomised, single-blinded intervention trial |journal=Lancet |volume=363 |issue=9409 |pages=600–7 |year=2004 |pmid=14987884 |doi=10.1016/S0140-6736(04)15591-8] However, a nonrandomized, observational study reported "limited, prognostic value" of the procalcitonin.cite journal |author=Brunkhorst FM, Al-Nawas B, Krummenauer F, Forycki ZF, Shah PM |title=Procalcitonin, C-reactive protein and APACHE II score for risk evaluation in patients with severe pneumonia |journal=Clin. Microbiol. Infect. |volume=8 |issue=2 |pages=93–100 |year=2002 |pmid=11952722|doi=10.1046/j.1469-0691.2002.00349.x]

References

External links

* [http://www.procalcitonin.com/ Procalcitonin] - web site of the manufacturer of the PCT assay.