key: cord-0867491-py9h6ktx
authors: Adams, Briony; Beaney, Alec
title: Interpreting serum procalcitonin in COVID-19 patients undergoing renal replacement therapy
date: 2021-11-12
journal: J Glob Antimicrob Resist
DOI: 10.1016/j.jgar.2021.09.014
sha: 23284acf276394fbc0fc62402f7ae67806f9ccdb
doc_id: 867491
cord_uid: py9h6ktx

nan

We read with interest the article by Heesom et al. on the use of procalcitonin (PCT) for antimicrobial stewardship in patients with COVID-19 (coronavirus disease 2019) [1] .

The data demonstrated that PCT was useful in guiding the duration of antibiotics for patients with concomitant bacterial infection.

Approximately 5% of COVID-19 patients require renal replacement therapy (RRT), including haemofiltration and dialysis protocols [2] . We are interested in the effect that this may have on the interpretation of PCT in this patient group.

Serum PCT levels may be affected by RRT, as the molecular weight of PCT is ~13 kDa and haemofiltration can remove molecules with molecular weight of up to 50 kDa [3] . This is particularly likely with higher flux membranes that have larger pore sizes and aim to remove larger molecules, including inflammatory mediators.

There is evidence that suggests PCT is removed from the serum via continuous venovenous haemofiltration (CVVHF) [4] . There are likely to be several influencing factors, including attenuation of the inflammatory response due to direct removal of cytokines or infective stimulus reduction by successful antibacterial therapies. Even allowing for these factors, it is thought that CVVHF is responsible for at least a portion of the serum PCT decrease [5] . Furthermore, the degree of PCT removal appears to be dependent on the membrane used, with a greater effect noted with high-flux membranes [6] .

In conclusion, evidence to date suggest that PCT is removed by RRT, however the extent of this effect on the serum PCT level is unclear. There is plausibly a risk that 

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Ethical approval: Not required.