Should I order serum procalcitonin on my patient with suspected infection?

Two things to ask before you order procalcitonin (PCT): 1. Will it impact patient management?; and 2. If so, will the result be available in a timely manner ie, within hours not days?

Whatever the result, PCT should always be interpreted in the context of the patient’s illness and other objective data. Not surprisingly then, as a “screening” test, PCT may be more useful in patients with low pre-test likelihood of having bacterial infection, not dissimilar to the use of D-dimer in patients with low pre-test probability of pulmonary embolism1.  

Several potential clinical uses of this biomarker have emerged in recent years,  including:1,2

  • Helping decide when to initiate antibiotics in patients with upper acute respiratory tract infections and bronchitis. A normal or low PCT supports viral infection.
  • Helping decide when to discontinue antibiotics (ie, when PCT normalizes) in community-acquired or ventilator-associated pneumonia.
  • Helping monitor patient progress with an expected drop in PCT of about 50% per day (half-life ~ 24 hrs) with effective therapy.

Few caveats…

  • PCT may be unremarkable in about a third of patients with bacteremia (especially due to less virulent bacteria, including many gram-positives)3.  
  • PCT levels are lowered by high-flux membrane hemodialysis, so check a baseline level before, not after, hemodialysis4.
  • Lastly, despite its higher specificity for bacterial infections compared to other biomarkers such as C-reactive protein, PCT may be elevated in a variety of non-infectious conditions, including pancreatitis, burns, pulmonary edema or aspiration, mesenteric infarction (ischemic bowel), cardiogenic shock, and hypotension during surgery2.

 

References:

  1. Schuetz P, Muller B, Chirst-Crain M, et al. Procalcitonin to initiate or discontinue antibiotics in acute respiratory tract infections (review). Evid-Based Child Health (A Cochrane Review Journal) 2013;8:4;1297-137. http://onlinelibrary.wiley.com/doi/10.1002/ebch.1927/pdf
  2. Gilbert GN. Use of plasma procalcitonin levels as an adjunct to clinical microbiology. J Clin Microbiol 2010;48:2325-29. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2897488/pdf/0655-10.pdf
  3. Yan ST, Sun LC, Jia HB. Procalcitonin levels in bloodstream infections caused by different sources and species of bacteria. Am J Emerg Med 2017;35:779-83. https://www.ncbi.nlm.nih.gov/m/pubmed/27979420/#fft
  4. Grace E, Turner RM. Use of procalcitonin in patients with various degrees of chronic kidney disease including renal replacement therapy. Clin Infect Dis 2014;59:1761-7. https://www.ncbi.nlm.nih.gov/pubmed/25228701
Should I order serum procalcitonin on my patient with suspected infection?

Should I routinely consider the possibility of pulmonary embolism (PE) in my patients hospitalized for syncope?

Syncope is a well-known initial manifestation of pulmonary embolism (PE)1.  However, given the varied causes of syncope, determining the prevalence of PE among patients hospitalized for syncope is important.   

A multicenter prospective study2 enrolled 560 patients not already on anticoagulation who were hospitalized for a first episode syncope.  Of patients who had either a high pretest probability for PE, positive D-dimer assay or both, PE was diagnosed in 17%, or nearly 1 of 6 of enrolled patients, based on CT or ventilation/perfusion scan. PE was found more frequently among patients with syncope of undetermined cause than those with an alternative explanation (25.4% vs 12.7%). 

Another multicenter prospective study (2019), however, found a much lower prevalence of PE (0.6%) among patients evaluated in the ED for syncope, including those who were not hospitalized.3 A related commentary on the article reported a prevalence of 4.1% in the total study population, assuming a “worst-case scenario calculation.” 4 

Given these divergent results, perhaps the best advice is to consider PE as cause of syncope in the proper context and minimize overtesting when suspicion remains low.

Liked this post? Download the app on your smart phone and sign up below to catch future pearls right into your inbox, all for free!

Subscribe to Blog via Email

Enter your email address to subscribe to this blog and receive notifications of new posts by email.

 

References 

  1. Thames MD, Alpert JS, Dalen JE. Syncope in patients with pulmonary embolism. JAMA 1977;238:2509-2511. https://www.ncbi.nlm.nih.gov/pubmed/578884
  2. Prandoni P, Lensing AWA, Prins MH, et al. Prevalence of pulmonary embolism among patients hospitalized for syncope. N Engl J Med 2016;375:1524-31. http://www.nejm.org/doi/full/10.1056/NEJMoa1602172
  3. Thiruganasambandamoorthy V, Sivilotti MLA, Rowe BH, et al. Prevalence of pulmonary embolism among emergency department patients with syncope: a multicenter prospective cohort study [published online January 25, 2019]. Ann Emerg Med. doi:10.106/j.annemergmed.2018. https://www.annemergmed.com/article/S0196-0644(18)31535-X/fulltext
  4. Anonymous. Pulmonary embolism uncommon in syncope hospitalizations. Pulmonology Advisor. February 6, 2019.  https://www.pulmonologyadvisor.com/pulmonary-embolism-uncommon-in-syncope-hospitalizations/printarticle/832069/

 

Contributed in part by Rebecca Berger  MD, Department of Medicine, Mass General Hospital, Boston, MA

 

Should I routinely consider the possibility of pulmonary embolism (PE) in my patients hospitalized for syncope?

My patient with significant dyspnea appears to have an acute exacerbation of his chronic obstructive pulmonary disease (AE-COPD). How often do AE-COPD and pulmonary embolism (PE) coexist?

Simultaneous presence of PE in patients with AE-COPD is not rare, particularly in those with unexplained AE-COPD.

A recent systematic review and meta-analysis reported a pooled PE prevalence of 16.1% (95% C.I. 8.3%-25.8%) in unexplained AE-COPD, with 68% of emboli found in the main pulmonary arteries, lobar arteries or inter-lobar arteries (i.e. not subsegmental); the pooled prevalence of deep venous thrombosis (DVT) was 10.5% (95% C.I. 4.3%-19.0%) 1. Pleuritic chest pain and signs of cardiac failure were associated with AE-COPD, while symptoms suggestive of a respiratory tract infection argued against PE.

It remains unclear, however, if the threshold for evaluation of venous thromboembolism (VTE) should necessarily differ between patients with explained vs unexplained AE-COPD.

In one small study, the prevalence of VTE in “unexplained” AE-COPD was significantly higher (25%) than “explained” AE-COPD (including cases with  tracheobronchitis, pneumonia, cardiac disorders, exposure to irritant inhalants, and lack of compliance with treatment), but the VTE prevalence for the latter group was still 8.4%2.  Serum D-dimer level and Wells criteria may help exclude VTE in this patient population.

Liked this post? Download the app on your smart phone and sign up below to catch future pearls right into your inbox, all for free!

Subscribe to Blog via Email

Enter your email address to subscribe to this blog and receive notifications of new posts by email.

 

References

  1. Aleva FE, Voets LWLM, Simons SO, et al. Prevalence and localization of pulmonary embolism in unexplained acute exacerbations of COPD: A systematic review and meta-analysis. CHEST (2016), doi: 10.1016/j.chest.2016.07.034.
  2. Gunen H, Gulbas G, In E, Yetkin O, Hacievliyagil SS. Venous thromboemboli and exacerbations of COPD. Eur Respir J 2010;35:1243-1248.

 

Contributed by Jeff Greenwald, MD, Core Educator Faculty, Department of Medicine, Massachusetts General Hospital

My patient with significant dyspnea appears to have an acute exacerbation of his chronic obstructive pulmonary disease (AE-COPD). How often do AE-COPD and pulmonary embolism (PE) coexist?