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Albumin: to be, or not to be, a buffer, that is the question
2023; American Physiological Society; Volume: 135; Issue: 1 Linguagem: Inglês
10.1152/japplphysiol.00288.2023
ISSN8750-7587
AutoresAimée Obolari Durço, Lino Sérgio Rocha Conceição, Diego Santos Souza,
Tópico(s)Potassium and Related Disorders
ResumoLetter to the EditorCall for Letters–Viewpoint: The buffer power of bloodAlbumin: to be, or not to be, a buffer, that is the questionAimée Obolari Durço, Lino Sergio Rocha Conceição, and Diego Santos SouzaAimée Obolari DurçoHealth Science Graduate Program, Federal University of Sergipe, Aracaju, Brazil, Lino Sergio Rocha ConceiçãoDepartment of Physical Therapy, Federal University of Sergipe, Universitary Hospital, Aracaju, Brazil, and Diego Santos SouzaDepartment of Biophysics, Federal University of Sao Paulo, Sao Paulo, BrazilPublished Online:27 Jun 2023https://doi.org/10.1152/japplphysiol.00288.2023MoreSectionsPDF (152 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat to the editor: Albumin is a protein that plays a crucial role in the acid-base balance in the body. Its amino acids contain functional groups that can donate positive and negative charges, which allows it to act as a buffering agent by neutralizing excess hydrogen ions and contributing to the maintenance of acid-base homeostasis. However, when discussing buffer power, two main mathematical formulas to describe the ability of a given agent to limit changes in pH, resulting from the addition of acids or bases (buffer power or "β"), seem to differ. The formulations in question by Van Slyke's β = d[A−]/dpH (βVS) and Stewart's β = A/d[H+] (βPS) are different in a few points; yet, despite mathematical controversy, in the end, after a correction in the effect of the initial hydrogen ion concentration in the βPS formula, both βVS and βPS increase with albumin concentration. Nonetheless, βVS is preferred for clinical use because, although it has a certain degree of a flaw in physical-chemical reasoning, it considers the buffering properties of the blood, instead of strictly considering the individual properties of each chemical agent (1).Although there has been a certain degree of agreement between Van Slyke and Stewart on the buffering power of albumin, the fact is that this issue is far from being resolved. Despite that albumin is indeed able to neutralize excess hydrogen ions and contribute to maintaining the body's acid-base balance, let's consider for a moment its chemical action, the fact that its concentration should be positively correlated with the meq/L value (per pH unit) of whole blood, as well as the chemical concept of a buffer (2, 3). Do not such weightings suggest that it is not a buffer?Albumin remains a controversial topic not only in theoretical studies but also in clinical practice. In critical care, for instance, albumin plays an important role both as a therapeutic agent and as a prognostic marker (4). There are several clinical scenarios for its use: hepatic disorders, traumatic brain injury, acute kidney injury, cardiac surgery, and sepsis. Most of these conditions incur in a high occurrence of morbidity and mortality—which may reflect (or not) the degree of albumin's power as a buffer. However, we should also bear in mind that albumin has several physiological effects such as: inhibition of platelet aggregation, antioxidant, maintenance of endothelial stability, anti-inflammatory, and as a carrier for many important molecules (4). An ongoing clinical trial about the effects of albumin in patients with sepsis is expected to be concluded in September 2023. Until then, most of the available data about the effect of albumin is controversial. So, we look forward to the "existential crisis" of albumin as a buffer being resolved (5).DISCLOSURESNo conflicts of interest, financial or otherwise, are declared by the authors.AUTHOR CONTRIBUTIONSA.O.D., L.S.R.C., and D.S.S. drafted manuscript; L.S.R.C. and D.S.S. edited and revised manuscript; A.O.D. and D.S.S. approved final version of manuscript.REFERENCES1. Giosa L, Zadek F, Langer T. The buffer power of blood: a reappraisal of its mathematical expressions with implications on the role of albumin as a buffer. J Appl Physiol (1985). doi:10.1152/japplphysiol.00083.2023.Link | Google Scholar2. Gatz R, Elbers P. Albumin is not a buffer in plasma. Blood Transfus 9: 107, 2011. doi:10.2450/2010.0015-10. Crossref | PubMed | ISI | Google Scholar3. Van Slyke DD. On the measurement of buffer values and on the relationship of buffer value to the dissociation constant of the buffer and the concentration and reaction of the buffer solution. J Biol Chem 52: 525–570, 1922. doi:10.1016/S0021-9258(18)85845-8.Crossref | Google Scholar4. Joannidis M, Wiedermann CJ, Ostermann M. Ten myths about albumin. Intensive Care Med 48: 602–605, 2022 [Erratum in Intensive Care Med 48: 793, 2022]. doi:10.1007/s00134-022-06655-8. Crossref | PubMed | ISI | Google Scholar5. Sakr Y, Bauer M, Nierhaus A, Kluge S, Schumacher U, Putensen C, Fichtner F, Petros S, Scheer C, Jaschinski U, Tanev I, Jacob D, Weiler N, Schulze PC, Fiedler F, Kapfer B, Brunkhorst F, Lautenschlaeger I, Wartenberg K, Utzolino S, Briegel J, Moerer O, Bischoff P, Zarbock A, Quintel M, Gattinoni L; SepNet - Critical Care Trials Group. Randomized controlled multicentre study of albumin replacement therapy in septic shock (ARISS): protocol for a randomized controlled trial. Trials 21: 1002, 2020. doi:10.1186/s13063-020-04921-y. Crossref | PubMed | ISI | Google ScholarAUTHOR NOTESCorrespondence: D. S. Souza (diegoenfsouza@hotmail.com). Download PDF Previous Back to Top Next FiguresReferencesRelatedInformation Related ArticlesThe buffer power of blood: a reappraisal of its mathematical expressions with implications on the role of albumin as a buffer 27 Jun 2023Journal of Applied Physiology More from this issue > Volume 135Issue 1July 2023Pages 201-201 Crossmark Copyright & PermissionsCopyright © 2023 the American Physiological Society.https://doi.org/10.1152/japplphysiol.00288.2023PubMed37368369History Received 5 May 2023 Accepted 8 May 2023 Published online 27 June 2023 Published in print 1 July 2023 Keywordsacid-base balancealbumin Metrics
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