Cytokines

My hospitalized patient with pneumonia has now suffered an acute myocardial infarction (MI). Can acute infection and MI be related?

FA Manian MD, MPH, , , , , , , , , Leave a comment

Yes! Ample epidemiological studies implicate infection as an important risk factor for MI.1 The increased risk of MI has been observed during the days, weeks, months or even years following an infection.

A 2018 paper reported a several-fold risk of MI during the week after laboratory-confirmed infection caused by a variety of respiratory pathogens such as influenza virus (6-fold), respiratory syncytial virus (4-fold), and other respiratory viruses (3-fold). 2 Among patients hospitalized for pneumococcal pneumonia, 7-8% may suffer an MI.3,4 One study found a 48-fold increase in the risk of MI during the first 15 days after hospitalization for acute bacterial pneumonia.5 Similarly, an increase in the short-term risk of MI has been observed in patients with urinary tract infection and bacteremia.6

The risk of MI appears to be the highest at the onset of infection and correlates with the severity of illness, with the risk being the highest in patients with pneumonia complicated by sepsis, followed by pneumonia and upper respiratory tract infection. Among patients with pneumonia, the risk exceeds the baseline risk for up to 10 years after the event, particularly with more severe infections.1

Potential mechanisms of MI following infections include release of inflammatory cytokines (eg, interleukins 1, 6, tumor necrosis factor alpha) causing activation of inflammatory cells in atherosclerotic plaques, in turn resulting in destabilization of the plaques. In addition, the thrombogenic state of acute infections, platelet and endothelial dysfunction may increase the risk of coronary thrombosis at sites of plaque disruption beyond clinical resolution of the acute infection. 1

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References

  1. Musher DM, Abers MS, Corrales-Medina VF. Acute infection and myocardial infarction. N Engl J Med 2019;380:171-6. https://www.ncbi.nlm.nih.gov/pubmed/30625066
  2. Kwong JC, Schwartz KL, Campitelli MA, et al. Acute myocardial infarction after laboratory-confirmed influenza infection. N Engl J Med 2018;378:345-53. https://www.nejm.org/doi/full/10.1056/NEJMoa1702090
  3. Musher DM, Alexandraki I, Graviss EA, et al. Bacteremic and nonbacteremic pneumococcal pneumonia: a prospective study. Medicine (Baltimore) 2000;79:210-21. https://www.ncbi.nlm.nih.gov/pubmed/10941350
  4. Musher DM, Rueda Am, Kaka As, Mapara SM. The association between pneumococcal pneumonia and acute cardiac events. Clin Infect Dis 2007;45:158-65. https://www.ncbi.nlm.nih.gov/pubmed/17578773
  5. Corrales-Medina VF, Serpa J, Rueda AM, et al. Acute bacterial pneumonia is associated with the occurrence of acute coronary syndromes. Medicine (Baltimore) 2009;88:154-9. https://www.ncbi.nlm.nih.gov/pubmed/19440118
  6. Dalager-Pedersen M, Sogaard M, Schonheyder HC, et al. Risk for myocardial infarction and stroke after community-acquired bacteremia: a 20-year population-based cohort study. Circulation 2014;129:1387-96. https://www.ncbi.nlm.nih.gov/pubmed/24523433

 

My hospitalized patient with pneumonia has now suffered an acute myocardial infarction (MI). Can acute infection and MI be related?

My patient with cirrhosis now has an upper gastrointestinal bleed (UGIB) with hepatic encephalopathy (HE). What’s the connection between UGIB and HE?

FA Manian MD, MPH, , , , , , , , , , , , , , , , , , , , , , , Leave a comment

Hepatic encephalopathy (HE) may be precipitated by a variety of factors including infection, hypovolemia, electrolyte imbalance (eg, hyponatremia, hypokalemia), metabolic alkalosis, sedatives, and of course UGIB. 1-3

Ammonia is often considered to play a central role in the the pathogenesis of HE, particularly when associated with UGIB. The ammoniagenic potential of UGIB is primarily attributed to the presence of hemoglobin protein in the intestinal tract. One-half of the ammoniagenesis originates from amino acid metabolism (mainly glutamine) in the mucosa of the small bowel, while the other half is due to the splitting of urea by the resident bacteria in the colon (eg, Proteus spp., Enterobacteriaceae, and anerobes).1,2

A large protein load in the GI tract, as occurs in UGIB, may result in hyperammonemia in patients with cirrhosis due to the limited capacity of the liver to convert ammonia to urea through the urea cycle as well as by the shunting of blood around hepatic sinusoids. Recent studies, however, also implicate the kidneys as an important source of ammonia in this setting, further compounding HE.3

It’s important to stress that ammonia is not likely to be the only mediator of HE. Enhanced production of cytokines due to infection or other inflammatory states, neurosteroids, endogenous benzodiazepines, and other bacterial byproducts may also play an important role in precipitating HE.2,4-6  So stay tuned!

Bonus pearl: Did you know that proinflammatory cytokines tumor necrosis factor-alpha and inerleukin-6 increase ammonia permeability across central nervous system-derived endothelial cells? 7

 

References

  1. Olde Damink SWM, Jalan R, Deutz NEP, et al. The kidney plays a major role in the hyperammonemia seen after simulated or actual GI bleeding in patients with cirrhosis. Hepatology 2003;37:1277-85.
  2. Frederick RT. Current concepts in the pathophysiology and management of hepatic encephalopathy. Gastroenterol Hepatol 2011;7:222-233.
  3. Tapper EB, Jiang ZG, Patwardhan VR. Refining the ammonia hypothesis: a physiology-driven approach to the treatment of hepatic encephalopathy. Mayo Clin Proc 2015;90:646-58.
  4. Shawcross DL, Davies NA, Williams R, et al. Systemic inflammatory response exacerbates the neuropsychological effects of induced hyperammonemia in cirrhosis. J Hepatol 2004;40:247-254.
  5. Shawcross DL, Sharifi Y, Canavan JB, et al. Infection and systemic inflammation, not ammonia, are associated with grade ¾ hepatic encephalopathy, but not mortality in controls. J Hepatol 2011;54:640-49.
  6. Shawcross D, Jalan R. The pathophysiologic basis of hepatic encephalopathy: central role for ammonia and inflammation.Cell Mol Life Sci 2005;62:2295-2304.
  7. Duchini A, Govindarajan S, Santucci M, et al. Effects of tumor necrosis factor-alpha and interleukin-6 on fluid-phase permeability and ammonia diffusion in CNS-derived endothelial cells. J Investig Med 1996;44:474-82.

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My patient with cirrhosis now has an upper gastrointestinal bleed (UGIB) with hepatic encephalopathy (HE). What’s the connection between UGIB and HE?

Can my patient develop “anemia of chronic disease” acutely while hospitalized?

FA Manian MD, MPH, , , , , , , , Leave a comment

“Anemia of chronic disease” is better termed anemia of inflammation (AI) which may occur in acute as well as chronic inflammatory states. 1 As such, the view that anemia in the critically ill patients is simply caused by excess phlebotomy is inaccurate. 2 The CRIT study demonstrated that AI in critically ill patients develops even within 30 days, often despite blood transfusions. 3

In addition to the usual causes of AI (eg autoimmune disorders), AI can occur during bacterial, viral or yeast infections and sepsis 4,5.

Recent studies implicate both iron sequestration and impaired erythropoiesis as causes of AI. 1 Inflammation stimulates hepatic production of iron-regulatory peptide, hepcidin, which decreases delivery of iron from macrophages to developing erythrocytes.  Inflammation also causes production of pro-inflammatory cytokine, IL-6, which suppresses erythropoiesis.

Couple of cool studies using injection of heat-killed Brucella abortus in mice as a model of AI, showed dramatic hemoglobin drop by 7 days.6,7. In addition, not only were iron restriction from increase in hepcidin and transient erythropoiesis demonstrated, erythrocyte lifespan was also shortened in these experiments. AI is truly a multifactorial process.

 

References 

  1. Frankel PG. Anemia of inflammation: A review. Med Clin N Ame 2017;101:285-96. https://www.ncbi.nlm.nih.gov/pubmed/28189171
  2. Corwin HL, Krantz SB. Anemia of the critically ill: “Acute” anemia of chronic disease. Crit Care Med 2000;28:3098-99. https://www.ncbi.nlm.nih.gov/pubmed/10966311
  3. Corwin HL, Gettinger A, Pearl RG, et al. The CRIT study: anemia and blood transfusion in the critically ill-current clinical practice in the United states. Crit Care Med 2004;32:39-52. https://www.ncbi.nlm.nih.gov/pubmed/14707558
  4. Gabriel A, Kozek S, Chiari A, et al. High-dose recombinant human erythropoietin stimulates reticulocyte production in patients with multiple organ dysfunction syndrome. J Trauma:Injury, Infection, and Critical Care 1998;44:361-67. https://www.ncbi.nlm.nih.gov/pubmed/9498512
  5. Roy CN. Anemia of inflammation. Hematology Am Soc Hematol Educ Program. 2010;2010:276-80. doi: 10.1182/asheducation-2010.1.276. https://www.ncbi.nlm.nih.gov/pubmed/21239806
  6. Kim A, Fung E, Parikh SG, et al. A mouse model of anemia of inflammation: complex pathogenesis with partial dependence on hepcidin. Blood 2014;123:1129-36. https://www.ncbi.nlm.nih.gov/pubmed/24357728
  7. Gardenghi S, Renaud TM, Meloni A, et al. Distinct roles for hepcidin and interleukin-6 in the recovery from anemia in mice injected with heat-killed Brucella abortus. Blood 2014;123:1137-45. https://www.ncbi.nlm.nih.gov/pubmed/24357729

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Can my patient develop “anemia of chronic disease” acutely while hospitalized?

My elderly nursing home patient is admitted with recent poor oral intake, falls and oral temperatures of 99.1°-99.3° F(37.3°-37.4°C). Is she considered febrile at these temperatures?

FA Manian MD, MPH, , , , , , Leave a comment

Yes! Even though we often think of temperatures of 100.4°F (38° C) or greater as fever, older people often fail to mount an appropriate febrile response despite having a serious infection. 1

Infectious Diseases Society of America (IDSA) guideline on evaluation of fever in older adult residents of long-term care facilities has defined fever in this population as:2

  • Single oral temperature >100° F (>37.8° C) OR
  • Repeated oral temperatures >99° F (>37.2° C) OR
  • Rectal temperatures >99.5° F (>37.5° C) OR
  • Increase in temperature of >2° F (>1.1° C) over the baseline temperature

Even at these lower than traditional thresholds for defining fever, remember that many infected elderly patients may still lack fever. In a study involving bacteremic patients, nearly 40% of those 80 years of age or older did not have fever (defined as maximum temperature over 24 hrs 100° F [37.8°C] or greater).3  

So our patient meets the criteria for fever as suggested by IDSA guidelines and, particularly in light of her recent poor intake and falls, may need evaluation for a systemic source of infection.

Bonus Pearl: Did you know that blunted febrile response of the aged to infections may be related to the inability of cytokines (eg, IL-1) to reach the central nervous system?1

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References 

  1. Norman DC. Fever in the elderly. Clin Infect Dis 2000;31:148-51. https://academic.oup.com/cid/article/31/1/148/318030
  2. High KP, Bradley SF, Gravenstein S, et al. Clinical practice guidelines for the evaluation of fever and infection in older adult residents of long-term care facilities: 2008 update by the Infectious Disease Society of America. Clin Infect Dis 2009;48:149-71. http://www.idsociety.org/uploadedFiles/IDSA/Guidelines-Patient_Care/PDF_Library/Fever%20and%20Long%20Term%20Care.pdf
  3. Manian FA. Fever, abnormal white blood cell count, neutrophilia, and elevated serum C-reactive protein in adult hospitalized patients with bacteremia. South Med J 2012;105;474-78. http://europepmc.org/abstract/med/22948327

 

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Mercy Hospital-St. Louis or its affiliate healthcare centers, Mass General Hospital, Harvard Medical School or its affiliated institutions. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

My elderly nursing home patient is admitted with recent poor oral intake, falls and oral temperatures of 99.1°-99.3° F(37.3°-37.4°C). Is she considered febrile at these temperatures?

What is the mechanism of anemia of chronic disease in my patient with rheumatoid arthritis?

FA Manian MD, MPH, , , , , , Leave a comment

Anemia of chronic disease (ACD)—or more aptly “anemia of inflammation”— is the second most common cause of anemia after iron deficiency and is associated with numerous acute or chronic conditions (eg, infection, cancer, autoimmune diseases, chronic organ rejection, and chronic kidney disease)1.

The hallmark of ACD is disturbances in iron homeostasis which result in increased uptake and retention of iron within cells of the reticuloendothelial system, with its attendant diversion of iron from the circulation and reduced availability for erythropoiesis1. More specifically, pathogens, cancer cells, or even the body’s own immune system stimulate CD3+ T cells and macrophages to produce a variety of cytokines, (eg, interferon-ɤ, TNF-α, IL-1, IL-6, and IL-10) which in turn increase iron storage within macrophages through induction of expression of ferritin, transferrin and divalent metal transporter 1.

In addition to increased macrophage storage of iron, ACD is also associated with IL-6-induced synthesis of hepcidin, a peptide secreted by the liver that decreases iron absorption from the duodenum and its release from macrophages2. TNF-α and interferon-ɤ also contribute to ACD by inhibiting the production of erythropoietin by the kidney.  Finally, the life span of RBCs is adversely impacted in AKD due to their reduced deformability and increased adherence to the endothelium in inflammatory states3.

Of interest, it is often postulated that by limiting access to iron through inflammation, the body hinders the growth of pathogens by depriving them of this important mineral2.

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References

  1. Weiss, G and Goodnough, L. Anemia of chronic disease. N Engl J Med 2005; 352; 1011-23. http://www.med.unc.edu/medclerk/medselect/files/anemia2.pdf
  2. D’Angelo, G. Role of hepcidin in the pathophysiology and diagnosis of anemia. Blood Res 2013; 48(1): 10-15. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3624997/pdf/br-48-10.pdf                                                                                                                                  
  3. Straat M, van Bruggen R, de Korte D, et al. Red blood cell clearance in inflammation. Transfus Med Hemother 2012;39:353-60. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3678279/pdf/tmh-0039-0353.pdf

 

Contributed by Amir Hossein Ameri, Medical Student, Harvard Medical School

                     

What is the mechanism of anemia of chronic disease in my patient with rheumatoid arthritis?

My patient with cirrhosis and suspected infection has a normal serum C-reactive protein (CRP). Does cirrhosis affect CRP response to infection?

FA Manian MD, MPH, , , , , , , , Leave a comment

CRP is primarily synthesized by the liver mainly as a response to IL-6 production in inflammatory states1.  Lower CRP production may then be expected in cirrhotic patients with significant infections and several studies support this view2. 

In a particularly convincing study involving E. coli-infected patients with bacteremia, the median CRP level in cirrhotic patients was about 40% that of non-cirrhotic patients (62 mg/L vs 146 mg/L)3.  In another study involving bacteremic patients with or without liver dysfunction, median CRP level was about 60% that of  patients with preserved liver function (81 mg/L vs 139 mg/L)4. 

Some investigators have reported a cut-off CRP value of 9.2 mg/L as a possible screening test for bacterial infections in patients with cirrhosis with a sensitivity and specificity of 88% (AUROC 0.93)5.

Collectively, these data suggest that although CRP response may be diminished in patients with advanced liver disease and acute infection, its synthesis is still maintained.

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 References

  1. Pieri G, Agarwal B, Burroughs AK. C-reactive protein and bacterial infection in cirrhosis. Ann Gastroenterol 2014;27:113-20. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3982625/pdf/AnnGastroenterol-27-113.pdf
  2. Ha YE, Kang C-I, Joo E-J, et al. Usefulness of C-reactive protein for evaluating clinical outcomes in cirrhotic patients with bacteremia. Korean J Intern Med 2011;26:195-200. http://pubmedcentralcanada.ca/pmcc/articles/PMC3110852/pdf/kjim-26-195.pdf
  3. Park WB1, Lee KD, Lee CS et al. Production of C-reactive protein in Escherichia coli-infected patients with liver dysfunction due to liver cirrhosis. Diagn Microbiol Infect Dis. 2005 Apr;51(4):227-30. https://www.ncbi.nlm.nih.gov/pubmed/15808312
  4. Mackenzie I, Woodhouse J. C-reactive protein concentrations during bacteraemia: a comparison between patients with and without liver dysfunction. Intensive Care Med 2006;32:1344-51. https://www.ncbi.nlm.nih.gov/pubmed/16799774
  5. Papp M, Vitalis Z, Altorjay I, et al. Acute phase proteins in the diagnosis and prediction of cirrhosis associated bacterial infection. Liver Int 2011;603-11. https://www.ncbi.nlm.nih.gov/pubmed/22145664

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Massachusetts General Hospital, Harvard Catalyst, Harvard University, its affiliate academic healthcare centers, or its contributors. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

 

My patient with cirrhosis and suspected infection has a normal serum C-reactive protein (CRP). Does cirrhosis affect CRP response to infection?

My patient with spontaneous bacterial peritonitis (SBP) is requiring IV albumin. Does IV albumin do anything other than expand the plasma volume?

FA Manian MD, MPH, , , , Leave a comment

Yes! Besides expanding the circulatory plasma volume by raising the oncotic pressure, albumin appears to have a vasoconstricting effects by binding to endotoxins, nitric oxide (NO), bilirubin and fatty acids1,2.

Splanchnic vasodilatation, a feature of decompensated cirrhosis (eg ascites, bleeding varices, hepatorenal syndrome, and hepatic encephalopathy), is accentuated by superimposed infections through cytokine-mediated release of endothelial vasodilators3.  By binding to potential vasodilators such as bile acids, endotoxins and NO, albumin may also help restore endothelial function and act as a vasoconstrictor.  

In a cool study involving patients with SBP randomized to either albumin or hydroxyethyl starch (HS, a synthetic volume expander), the albumin (not HS) group had a significant increase in mean arterial pressure, right atrial pressure, pulmonary artery pressure,  systolic volume, left ventricular stroke work, and systemic vascular resistance3.

Albumin may also have an immune-modulating activity in patients with cirrhosis or acute liver decompensation by binding to prostaglandin E-2 (PGE-2), generated as a result of inflammatory reaction in the liver and bacterial translocation4.  PGE-2 is a suppressor of macrophage cytokine secretion and bacterial killing.  By binding to PGE-2, albumin can reverse this immunosuppression by reducing the availability of serum PGE-2.

References

  1. Baraldi O, Valenini C, Donati G, et al. Hepatorenal syndrome: update on diagnosis and treatment 2015;4:511-20. https://www.ncbi.nlm.nih.gov/pubmed/26558188
  2. Angeli P, Volpin R, Piovan D, et al. Acute effects of the oral administration of midodrine, an α-adrenergic agonist, on renal hemodynamics and renal function in cirrhotic patients with ascites. Hepatology 1998;28:937-43. https://www.ncbi.nlm.nih.gov/pubmed/9755229
  3. Fernandez J, Monteagudo J, Bargallo X, et al. A randomized unblended pilot study comparing albumin versus hydroxyethyl starch in spontaneous bacterial peritonitis. Hepatology 2005;42:627-634. https://www.ncbi.nlm.nih.gov/pubmed/16108036
  4. Gleeson, MW, Dickson RC. Albumin gains immune boosting credibility. Clin Transl 2015;6:e86;doi:10.1038/ctg.2015.11. http://www.nature.com/ctg/journal/v6/n4/full/ctg201511a.html
My patient with spontaneous bacterial peritonitis (SBP) is requiring IV albumin. Does IV albumin do anything other than expand the plasma volume?

What is the connection between cirrhosis and adrenal insufficiency (AI)?

FA Manian MD, MPH, , , , , , , , , Leave a comment

The prevalence of AI in patients with liver disease varies widely (30-60%). 1  However, there is no consensus on how to define AI in such patients, nor is the methodology for its evaluation standardized. 

A common criticism is the frequent reliance on total, not free, serum cortisol in cirrhosis which may overestimate the prevalence of AI because cortisol is bound to corticosteroid binding globulin and albumin, commonly found at lower concentrations in cirrhosis. However, even when based on measuring free cortisol, AI is found in 12%-29% of clinically stable cirrhotic patients. 1

 Secondary AI due to hypothalamic-pituitary dysfunction has also been reported in Child-Pugh class A, B, and C patients (42%, 69%, and 80%, respectively). 2

The mechanism of AI in cirrhosis is unclear, but low serum cholesterol in cirrhosis leading to lack of substrate for steroidogenesis, and increased levels of circulating endotoxin and pro-inflammatory cytokines impairing the hypothalamic-pituitary-adrenal axis have been postulated. 1

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References

  1. Fede G, Spadaro L, Purrello F. Review: adrenal insufficiency in liver disease. J Liver 2014;3:1. https://www.ncbi.nlm.nih.gov/pubmed/22234976
  2. Zietz, B, Lock, G, Plach, B, et al. Dysfunction of the hypothalamic-pituitary-glandular axes and relation to Child-Pugh classification in male patients with alcoholic and virus-related cirrhosis. Eur J Gastroenterol Hepatology 2003;15:495-501. https://www.ncbi.nlm.nih.gov/pubmed/12702906
What is the connection between cirrhosis and adrenal insufficiency (AI)?

How is the pathophysiology of sepsis-associated acute kidney injury (SA-AKI) different than AKI due to non-septic conditions?

FA Manian MD, MPH, , , , Leave a comment

Sepsis accounts for up to one-half of AKI cases in developed countries1.  Although sepsis-mediated hypoperfusion causing tubular necrosis has traditionally been implicated as the primary basis for SA-AKI,  an increasing number of studies have suggested that SA-AKI is a distinct subset of AKI differentiated from other causes by unique hemodynamic and inflammatory/immune-related mechanisms.  

Many animal and limited human studies have found that renal blood flow is an inconsistent predictor of SA-AKI, possibly related to the redistribution of blood in the renal microvasculature to the detriment of the renal medulla in sepsis2.

Cytokine-mediated response in sepsis can also lead to tubular cellular injury without necessarily causing necrosis. Of interest, an autopsy study found histological features of acute tubular necrosis in only 22% of patients with clinical diagnosis of SA-AKI 3.  

Differences in its pathophysiology may at least in part explain why oliguria, renal function recovery, hemodialysis and death are more common among SA-AKI patients4.

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References

  1. Alobaidi R, Basu RK, Goldstein SL, Bagshaw SM. Sepsis-associated acute kidney failure. Semin Nephrol 2015;35:2-11.  https://www.ncbi.nlm.nih.gov/pubmed/25795495
  2. Maiden MJ, Otto S, Brealey JK, et al. Structure and function of the kidney in septic shock. Am J Resp Crit Care Med 2016;194:692-700. https://www.atsjournals.org/doi/abs/10.1164/rccm.201511-2285OC
  3. Langenberg C, Bagshaw SM, May CN, Bellomo R. The histopathology of septic acute kidney injury: a systemic review. Crit Care 2008;12:R38.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2447560/
  4. Cruz MG, de Oliveira Dantas JGA, Levi TM, et al. Septic versus non-septic acute kidney injury in critically ill patients: characteristics and clinical outcome. Rev Bras Ter Intensiva 2014;26:384-391. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4304467/
How is the pathophysiology of sepsis-associated acute kidney injury (SA-AKI) different than AKI due to non-septic conditions?

What is the rationale for using N-acetylcysteine (NAC) in the treatment of non-acetaminophen-related liver failure (NALF)?

FA Manian MD, MPH, , , , , Leave a comment

Although  the evidence on the effectiveness of NAC in NALF has often been inconclusive, an 2021 meta-analysis and systematic review of the role of NAC in NALF concluded that NAC significantly improves overall survival, post-transplant survival and transplant-free survival while decreasing the overall length of hospital stay (1). 

This meta-analysis included 7 studies involving 883 patients with a mean age of 21 years in the NAC group. Significantly higher overall survival (O.R. 1.8), post-transplant survival (O.R. 2.4) and transplant-free survival (O.R. 2.9) were observed in the NAC group. 

Previously, a 2009 randomized-controlled study involving adults with NALF (including many due to drug toxicity, hepatitis B virus-HBV, and autoimmune causes) had found longer transplant-free survival—not overall survival—in the treatment group, especially among those with lower grade encephalopathy, or liver failure caused by drugs or HBV (2). 

Although it’s not clear how NAC might work in the setting of of NALF, possible effect on microcirculation or 02 delivery through interference with cytokines or other mechanisms have been suggested (2,3).  An interesting 2013 article reported lower serum levels of interleukin-17 among treated patients (3)!

Bonus Pearl: Did you know that acute liver failure affects 2000-3000 persons in the U.S. each year with a mortality as high as 30%? (3)

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References

  1. Walayat S, Shaoib H, Asghar M, et al. Role of N-acetylcysteine in non-acetominophen-related acute liver failure: an updated meta-analysis and systematic review. Ann Gastroenterol 2021;34, 1-6. http://www.annalsgastro.gr/files/journals/1/earlyview/2021/ev-01-2021-04-AG_5321-0571.pdf 
  2. Bass S, Zook N. Intravenous acetylcysteine for indications other than acetaminophen overdose. Am J Health-Syst Pharm 2013;70:1496-1501. https://www.ncbi.nlm.nih.gov/pubmed/23943180
  3. Stravitz RT, Sanyal AJ, Reisch J, et al. Effects of N-acetylcysteine on cytokines in non-acetaminophen acute liver failure: potential mechanism of improvement in transplant-free survival. Liver Int. 2013;33:1324-1331. https://utsouthwestern.pure.elsevier.com/en/publications/effects-of-n-acetylcysteine-on-cytokines-in-non-acetaminophen-acu

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Mercy Hospital-St. Louis or its affiliate healthcare centers, Mass General Hospital, Harvard Medical School or its affiliated institutions. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

 

What is the rationale for using N-acetylcysteine (NAC) in the treatment of non-acetaminophen-related liver failure (NALF)?