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Critical Care

, 23:5 | Cite as

Dosing adjuvant vitamin C in critically ill patients undergoing continuous renal replacement therapy: We are not there yet!

  • Patrick M. HonoreEmail author
  • David De Bels
  • Luc Kugener
  • Sebastien Redant
  • Rachid Attou
  • Andrea Gallerani
  • Herbert D. Spapen
Open Access
Letter

Abbreviations

CRRT

Continuous renal replacement therapy

CVVH

Continuous veno-venous hemofiltration

CVVHD

Continuous veno-venous hemodialysis

CVVHDF

Continuous veno-venous hemodiafiltration

IV

Intravenous

Vit C

Vitamin C

We read with great interest the recent letter to Critical Care by Marik and Hooper [1]. Vitamin C (vit C) is increasingly recognized as a crucial compound to alleviate morbidity in critically ill patients. Vit C concentrations, however, are usually far below normal and even close to “scurvy levels” in this population. Vit C also is substantially cleared by continuous renal replacement therapy (CRRT). Significant vit C deficiency was observed in 80% of patients subjected to various types of CRRT despite receiving a daily intravenous (IV) supplement of 500 to 1000 mg [2]. Therefore, high-dose (from 6 to 12 g) vit C substitution during CRRT seems justified [3].

Marik and Hooper argued against such dose increase in patients receiving CRRT. To support their statement, they provided serum vit C dosages in a small number of septic patients who received 6 g vit C IV while undergoing continuous veno-venous hemofiltration (CVVH). Vit C trough and peak levels were largely above normal and comparable to levels obtained in patients not receiving CVVH [1].

We want to warn against oversimplification. Marik and Hooper measured vit C within 30 min after the end of vit C infusion. It would have been more relevant to measure vit C after 24 to 48 h of CVVH treatment. Up to 50% of vit C is cleared in a time-dependent manner during a 4-h session of intermittent hemodialysis or hemodiafiltration [4, 5], which suggests that continuous techniques may exacerbate vit C losses. Vit C also is eliminated by both diffusion (dialysis) and convection (filtration). During hemodiafiltration, diffusion is responsible for two thirds of the vit C loss whereas convection accounts only for one third [5]. CVVH is a sheer convective technique in contrast with other often-used CRRT modes in the critically ill, such as continuous veno-venous hemodialysis (CVVHD) and continuous veno-venous hemodiafiltration (CVVHDF). Marik and Hooper thus report the most modest way of CRRT-induced vit C elimination. It is reasonable to think that more diffusion-based CRRT techniques may yield other results.

We agree with Marik and Hooper that 6 g/day vit C IV is sufficient for patients without acute kidney injury and not requiring CRRT. However, vit C measurements should be performed after prolonged CVVH sessions to ensure that a 6 g daily supplement can keep levels within normal range. More studies are needed in patients receiving CVVHD or CVVHDF to exclude overlooking too great a vit C loss.

Notes

Acknowledgments

None.

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Authors’ contributions

PMH and HDS designed the paper. All authors participated in drafting and reviewing and read and approved the final version of the manuscript.

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Not applicable.

Competing interests

The authors declare that they have no competing interests.

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References

  1. 1.
    Marik PE, Hooper MH. Adjuvant Vitamin C in critically ill patients undergoing renal replacement therapy: What's the right dose? Crit Care. 2018;22:320.  https://doi.org/10.1186/s13054-018-2190-y. No abstract available.CrossRefPubMedPubMedCentralGoogle Scholar
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    Kamel AY, Dave NJ, Zhao VM, Griffith DP, Connor MJ Jr, Ziegler TR. Micronutrient Alterations During Continuous Renal Replacement Therapy in Critically Ill Adults: A Retrospective Study. Nutr Clin Pract. 2018;33:439–46.  https://doi.org/10.1177/0884533617716618 Epub 2017 Dec 18.CrossRefPubMedGoogle Scholar
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    Honore PM, De Bels D, Preseau T, Redant S, Attou R, Spapen HD. Adjuvant vitamin C in cardiac arrest patients undergoing renal replacement therapy: an appeal for a higher high-dose. Crit Care. 2018;22:207.  https://doi.org/10.1186/s13054-018-2115-9. CrossRefPubMedPubMedCentralGoogle Scholar
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    Fehrman-Ekholm I, Lotsander A, Logan K, Dunge D, Odar-Cederlöf I, Kallner A. Concentrations of vitamin C, vitamin B12 and folic acid in patients treated with hemodialysis and on-line hemodiafiltration or hemofiltration. Scand J Urol Nephrol. 2008;42:74–80.  https://doi.org/10.1080/00365590701514266.CrossRefPubMedGoogle Scholar
  5. 5.
    Morena M, Cristol JP, Bosc JY, Tetta C, Forret G, Leger CL, et al. Convective and diffusive losses of vitamin C during haemodiafiltration session: a contributive factor to oxidative stress in haemodialysis patients. Nephrol Dial Transplant. 2002;17:422–7.CrossRefGoogle Scholar

Copyright information

© The Author(s). 2019

Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Authors and Affiliations

  • Patrick M. Honore
    • 1
    Email author
  • David De Bels
    • 1
  • Luc Kugener
    • 1
  • Sebastien Redant
    • 1
  • Rachid Attou
    • 1
  • Andrea Gallerani
    • 1
  • Herbert D. Spapen
    • 2
  1. 1.ICU DepartmentCentre Hospitalier Universitaire Brugmann-Brugmann University HospitalBrusselsBelgium
  2. 2.Ageing & Pathology Research GroupVrije Universiteit BrusselBrusselsBelgium

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