When should I consider Pseudomonas aeruginosa as a cause of respiratory tract infection in my hospitalized patient with COPD exacerbation?

The most consistent risk factor for isolation of P. aeruginosa from sputum of adults with COPD is the presence of more advanced pulmonary disease (eg, FEV-1 <35-50%) or functional impairment (1-5).

 

Chronic corticosteroid use is also frequently cited as an important predictor of respiratory tract colonization/infection due to P. aeruginosa in patients with COPD, while the data on antibiotic use during the previous months have been conflicting (2,4). Other risk factors may include prior isolation of P. aeruginosa and hospital admission during the previous year (1).

 
A prospective study of patients hospitalized for COPD exacerbation found P. aeruginosa to be the most frequently isolated organism, growing from 26% of validated sputum samples at initial admission, followed by Streptococcus pneumoniae and Hemophilus influenzae. In the same study, bronchiectasis (present in up to 50% of patients with COPD) was not shown to be independently associated with the isolation of P. aeruginosa (1).

 
Of interest, compared to the patients without P. aeruginosa, patients hospitalized for acute exacerbation of COPD and isolation of P. aeruginosa from sputum have significantly higher mortality: 33% at 1 year, 48% at 2 years and 59% at 3 years (5).

 
References
1. Garcia-Vidal C, Almagro P, Romani V, et al. Pseudomonas aeruginosa in patients hospitalized for COPD exacerbation: a prospective study. Eur Respir J 2009;34:1072-78. https://www.ncbi.nlm.nih.gov/pubmed/19386694
2. Murphy TF. Pseudomonas aeruginosa in adults with chronic obstructive pulmonary disease. Curr Opin Pulm Med 2009;15:138-42. https://www.ncbi.nlm.nih.gov/pubmed/19532029
3. Miravitlles M, Espinosa C, Fernandez-Laso E, et al. Relationship between bacterial flora in sputum and functional impairment in patients with acute exacerbations of COPD. Chest 1999;116:40-6. https://www.ncbi.nlm.nih.gov/pubmed/10424501
4. Murphy TF, Brauer AL, Eschberger K, et al. Pseudomonas aeruginosa in chronic obstructive pulmonary disease. Am J Respir Crit Care Med 2008;177:853-60. https://www.ncbi.nlm.nih.gov/pubmed/18202344
5. Almagro P, Silvado M, Garcia-Vidal C, et al. Pseudomonas aeruginosa and mortality after hospital admission for chronic obstructive pulmonary disease. Respiration 2012;84:36-43. https://www.karger.com/Article/FullText/331224

 

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When should I consider Pseudomonas aeruginosa as a cause of respiratory tract infection in my hospitalized patient with COPD exacerbation?

Is my hospitalized patient with possible pneumonia at risk of Clostridium difficile-associated disease after only 1-3 days of empiric antibiotic therapy?

Yes! Even relatively brief duration of antibiotic therapy may increase the risk of Clostridium difficile-associated disease (CDAD) in a susceptible host.
In a study of hospitalized patients with new-onset diarrhea, prior exposure to levofloxacin and cefazolin was significantly associated with CDAD with the median duration of therapy for levofloxacin of 3 days (range 1-18 days), and for cefazolin 2 days (range 1-3 days) (1). Similarly, a study in hospitalized patients during a CDAD epidemic found a significantly increased risk of CDAD among patients who received fluoroquinolones for only 1-3 days (hazard ratio 2.4) with a 95% confidence interval (1.6-3.6) that overlapped 4-6 days and ≥ 7 days treatment groups (2). Yet another study found no significant difference in the risk of CDAD between those on antibiotic for < 4 days vs 4-7 days of antibiotics (3). CDAD following a single dose of cefazolin has also been reported (4).
Of interest, laboratory studies in mice have shown a profound alteration of intestinal microbiota following a single dose of clindamycin, resulting in increased susceptibility to C. difficile colitis (5).
So although duration of antibiotic therapy is an important factor in CDAD (3, 6) and we should minimize the duration of antibiotic therapy whenever possible, not starting antibiotics in the absence of clear indication is even better!

References
1. Manian FA, Aradhyula S, Greisnauer S, et al. Is it Clostridium difficile infection or something else? A case-control study of 352 hospitalized patients with new-onset diarrhea. S Med J 2007;100:782-786. https://www.ncbi.nlm.nih.gov/pubmed/17713303
2. Pepin J, Saheb N, Coulombe MA, et al. Emergence of fluoroquinolones as the predominant risk factor for Clostridium difficile-associated diarrhea: a cohort study during an epidemic in Quebec. Clin Infect Dis 2005;41:1254-60. https://www.ncbi.nlm.nih.gov/pubmed/16206099
3. Stevens V, Dumyati G, Fine LS, et al. Cumulative antibiotic exposures over time and the risk of Clostridium difficile infection. Clin Infect Dis 2011;53:42-48. https://www.ncbi.nlm.nih.gov/pubmed/21653301
4. Mcneeley SG, Anderson GD, Sibai BM. Clostridium difficile colitis associated with single dose cefazolin prophylaxis. Ob Gynecol 1985;66:737-8. https://www.ncbi.nlm.nih.gov/pubmed/4058831
5. Buffie CG, Jarchum I, Equinda M, et al. Profound alterations of intestinal microbiota following a single dose of clindamycin results in sustained susceptibility to Clostridium difficile-induced colitis. Infect Immun 2011;80: 62-73. https://www.ncbi.nlm.nih.gov/pubmed/22006564
6. Chalmers JD, Akram AR, Sinanayagam A, et al. Risk factors for Clostridium difficile infection in hospitalized patients with community-acquired pneumonia. J Infect 2016;73:45-53. https://www.ncbi.nlm.nih.gov/pubmed/27105657

Disclosure: The contributor of this post was a coinvestigator of a cited study (ref. 1).

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Is my hospitalized patient with possible pneumonia at risk of Clostridium difficile-associated disease after only 1-3 days of empiric antibiotic therapy?

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

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?

My previously healthy patient is admitted with a multi-drug resistant E. coli urinary tract infection. Could her urinary tract infection (UTI) be foodborne?

Yes! Although foodborne infections are often thought to cause infections limited to the GI tract, an increasing number of studies have linked foodborne E.coli to extraintestinal infections in humans, including UTIs.1

Supportive data include frequent genetic similarly between antimicrobial-resistant E. coli from humans and poultry-associated E. coli. 2 In fact, antimicrobial-resistant E. coli isolates from humans may be  genetically more similar to poultry isolates than susceptible commensal E. coli strains in the human GI tract.3

A U.S. study found that 14% of chicken meat products were contaminated with E. coli strains capable of causing extraintestinal disease, 1/3 of which were mutli-drug resistant.4  Another study found that 94% of retail chicken meat samples contained E. coli with ESBL-genes,  of which nearly 40% contained isolates present in humans.5

Among women, UTI caused by antimicrobial-resistant extraintestinal pathogenic E. coli has been linked to high levels of self-reported chicken consumption.6

The plausibility of foodborne transmission of antimicrobial-resistant E. coli to humans is further supported by the finding that drug resistant E coli from chicken carcasses widely contaminate the kitchen during meal preparation and can appear in the intestinal tract of those who prepare such food.2

Bonus Pearl: Did you know that women with multi-drug resistant E. coli UTI are 3.7 times more likely to report frequent consumption of chicken? 6

References

  1. Manges AR. Escherichia coli and urinary tract infections: the role of poultry-meat. Clin Microbiol Infect 2016;22:122-29. https://www.ncbi.nlm.nih.gov/pubmed/26679924
  2. Manges AR, Johnson JR. Reservoirs of extraintestinal pathogenic Escherichia coli. Microbiol Spectrum 2012;3(5):UTI-0006-2012. https://www.ncbi.nlm.nih.gov/pubmed/26542041
  3. Johnson JR, Menard M, Johsnton B, et al. Epidemic clonal groups of Escherichia coli as a cause of antimicrobial-resistant urinary tract infections in Canada, 2002 to 2004. Antimicrob Agents Chemother 53;2733-2739. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2704706/
  4. Johnson JR, Porter SB, Johnston B, et al. Extraintestinal pathogenic and antimicrobial-resistant Escherichia coli, including sequence type 131 (ST131) from retail chicken breasts in the United States in 2013. Apppl Environ Microbiol 83:e02956-16. https://www.ncbi.nlm.nih.gov/pubmed/28062464
  5. Leverstein-van Hall MA, Dierikx CM, Stuart JC, et al. Dutch patients, retail chicken meat and poultry share the same ESBL genes, plasmids and strains. Clin Microbiol Infect 2011;17:873-880. https://www.ncbi.nlm.nih.gov/pubmed/21463397
  6. Manges AR, Smith SP, Lau BJ, et al. Retail meat consumption and the acquisition of antimicrobial resistant Escherichia coli causing urinary tract infections: a case-control study. Foodborne Path Dis 4:419-431. https://www.ncbi.nlm.nih.gov/pubmed/18041952

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My previously healthy patient is admitted with a multi-drug resistant E. coli urinary tract infection. Could her urinary tract infection (UTI) be foodborne?

Should my hospitalized patient with ulcerative colitis flare-up receive pneumococcal vaccination?

There are at least 2 reasons for considering pneumococcal vaccination in hospitalized patients with ulcerative colitis flare.

First, these patients are often on immunosuppressants (eg, glucocorticoids) or biological agents (eg, infliximab) that qualifies them for both 13-valent conjugate (PCV13) and 23-valent polysaccharide (PPSV23) pneumococcal vaccines under the Advisory Committee on Immunization Practices (ACIP) Guidelines’ “Immunocompromised persons” risk group.1-4

Another reason is the possibility of  UC patients having coexisting hyposplenism, a major risk factor for pneumococcal disease. Although this association has been described several times in the literature since 1970s, it is relatively less well known.  In a study of patients with UC, hyposplenism (either by the presence of Howell-Jolly bodies in the peripheral blood smear or prolongation of clearance from blood of injected radioactively labelled heat-damaged red blood cells) was found in over one-third with some developing life-threatening septicemia in the early postcolectomy period.5 Another study found the majority of patients with UC having slow clearance of heat damaged RBCs despite absence of Howell-Jolly bodies in the peripheral smear.6 Fulminant and fatal pneumococcal sepsis has also been reported in patients with UC.7

Although the immunological response to pneumococcal vaccination may be lower among immunosuppressed patients in general, including those with UC, it should still be administered to this population given its potential benefit in reducing the risk of serious pneumococcal disease. 2,3  

References

  1. CDC. Intervals between PCV13 and PSV23 vaccines: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 2015;64:944-47. https://www.cdc.gov/mmwr/preview/mmwrhtml/mm6434a4.htm
  2. Carrera E, Manzano r, Garrido. Efficacy of the vaccination in inflammatory bowel disease. World J Gastroenterol 2013;19:1349-53. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3602493/
  3. Reich J, Wasan S, Farraye FA. Vaccinating patients with inflammatory bowel disease. Gastroenterol Hepatol 2016;12:540-46. http://www.gastroenterologyandhepatology.net/archives/september-2016/vaccinating-patients-with-inflammatory-bowel-disease/
  4. Chaudrey K, Salvaggio M, Ahmed A, et al. Updates in vaccination: recommendations for adult inflammatory bowel disease patients. World J Gastroenterol 2015;21:3184-96. https://www.ncbi.nlm.nih.gov/pubmed/25805924
  5. Ryan FP, Smart RC, Holdworth CD, et al. Hyposplenism in inflammatory bowel disease. Gut 1978;19:50-55. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1411782/
  6. Jewell DP, Berney JJ, Pettit JE. Splenic phagocytic function in patients with inflammatory bowel disease. Pathology 1981;13:717-23. https://www.ncbi.nlm.nih.gov/pubmed/7335378
  7. Van der Hoeven JG, de Koning J, Masclee AM et al. Fatal pneumococcal septic shock in a patient with ulcerative colitis. Clin Infec Dis 1996;22:860-1. https://www.ncbi.nlm.nih.gov/pubmed/8722951

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Should my hospitalized patient with ulcerative colitis flare-up receive pneumococcal vaccination?

Should I consider fosfomycin in the treatment of urinary tract infection in my male patient with suspected prostatitis?

Although fosfomycin (FM) has been approved by the FDA only for the treatment of uncomplicated urinary tract infection (UTI) in women, it may also have a role in the treatment of acute and chronic prostatitis among males given its favorable levels in the prostate tissue. 1-5

Despite lack of studies comparing the efficacy of FM with that of commonly used antibiotics for treatment of prostatitis, the potential utility of FM is supported by several reports of its efficacy in the treatment of prostatitis, including those caused by extended-spectrum beta-lactamase (ESBL)-producing gram-negative rods. 1,4-5

When considering FM for treatment of prostatitis, a higher dose than customary may be needed (3 g once daily, not every 48-72 h) . 4 Although the optimal duration of therapy with FM is unclear in this setting, 12-16 weeks of therapy was used in 2 patients with recurrent UTIs and prostatitis due to multi-drug resistant ESBL-positive E. coli. 4

Given its pharmacokinetics and lack of proven efficacy, avoid FM in pyelonephritis, perinephric abscess or UTI with bacteremia. 2

References

  1. Falagas ME, Vouloumanou EK, Samonis G, et al. Fosfomycin. Clin Microbiol Rev 2016;29:321-347. https://www.ncbi.nlm.nih.gov/pubmed/26960938
  2. Wankum M, Koutsari C, Gens K. Fosfomycin use. Pharmacy Times. November 30, 2017. https://www.pharmacytimes.com/publications/health-system-edition/2017/november2017/fosfomycin-use
  3. Cunha BA, Gran A, Raza M. Persistent extended-spectrum β-lactamase-positive Escherechia coli chronic prostatitis successfully treated with a combination of fosfomycin and doxycycline. International J Antimicrob Agents 2015;45:427-29. https://www.ncbi.nlm.nih.gov/pubmed/25662814
  4. Grayson ML, Macesic N, Trevillyan J, et al. Fosfomycin for treatment of prostatitis: new tricks for old dogs. Clin Infect Dis 2015;61:1141-3. https://www.ncbi.nlm.nih.gov/pubmed/26063723
  5. Falagas ME, Rafailidis PI. Fosfomycin: the current status of the drug. Clin Infect Dis 2015;61:1144-6. https://www.ncbi.nlm.nih.gov/pubmed/26063717
Should I consider fosfomycin in the treatment of urinary tract infection in my male patient with suspected prostatitis?

Does erythrocyte sedimentation rate (ESR) have diagnostic utility in my patient with chronic renal failure?

Short answer: No! This is because most studies have shown frequently high ESR’s in stable “uninflamed” patients with chronic renal failure (CRF) (including those on dialysis) at levels often associated with infection, connective tissue disease, or malignancy in normal renal function. 1-4  

In fact, in a study involving patients with CRF, 57% of patients had markedly elevation of ESR (greater than 60 mm/h), with 20% having ESR greater than 100 mm/h; type or duration of dialysis had no significant effect on ESR levels.1 Another study reported a specificity for abnormal ESR of only 35% for commonly considered inflammatory conditions (eg, infections or malignancy) among patients with CRF. 2

But is it the chronic inflammation in diseased kidneys or the uremic environment that elevates ESR? A cool study compared ESR in CRF in patients who had undergone bilateral nephrectomies with those with retained kidneys and found no significant difference in the ESR between the 2 groups. 4  So it looks like it’s the uremic environment, not diseased kidneys themselves that result in elevated ESR in these patients.

The mechanism behind these observations seem to reside entirely within the patients’ plasma, not the erythrocytes. Within the plasma, fibrinogen (not gammaglobulins) seem to be the most likely factor explaining elevated ESR among patients with CRF. 1,2

Bonus pearl:  Did you know that ESR is nearly 100 years old, first described in 1921? 5

References

  1. Barthon J, Graves J, Jens P, et al. The erythrocyte sedimentation rate in end-stage renal failure. Am J Kidney Dis 1987;10: 34-40. https://www.ncbi.nlm.nih.gov/pubmed/3605082
  2. Shusterman N, Morrison G, Singer I. The erythrocyte sedimentation rate and chronic renal failure. Ann Intern Med 1986;105:801. http://annals.org/aim/fullarticle/700910
  3. Arik N, Bedir A, Gunaydin M, et al. Do erythrocyte sedimentation rate and C-reactive protein levels have diagnostic usefulness in patients with renal failure? Nephron 2000;86:224. https://www.ncbi.nlm.nih.gov/pubmed/11015011
  4. Warner DM, George CRP. Erythrocyte sedimentation rate and related factors in end-stage renal failure. Nephron 1991;57:248. https://www.karger.com/Article/PDF/186266
  5. Fahraeus R. The suspension stability of the blood. Acta Med Scan 1921;55:70-92. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.0954-6820.1921.tb15200.x

 

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Does erythrocyte sedimentation rate (ESR) have diagnostic utility in my patient with chronic renal failure?

Why is latent tuberculosis usually treated with one antibiotic while active tuberculosis is treated with 2 or more drugs?

Conventional wisdom has been that in active tuberculosis (TB) patients harbor large numbers of replicating Mycobacterium tuberculosis (Mtb), requiring multiple antibiotics to prevent the emergence of resistant mutants. In contrast, Mtb under latent or “inactive” conditions is presumed to have little capacity for mutation due to reduced bacterial replication, thus generally requiring only one antibiotic for preventive therapy.1

However, the assumption that Mtb has a low capacity for mutation in latent TB due to slow bacterial replication has been challenged in recent years. An experimental study in macaque monkeys with latent Mtb infection using whole genome sequencing demonstrated that despite reduced replication, Mtb acquires a similar number of chromosomal mutations during latency as it does during active infection.1

This finding supports the more current and evolving concept of latent TB which assumes diverse mycobacterial growth states, ranging from complete absence of organisms to actively replicating bacterial populations.2 It also explains why, although effective, isoniazid monotherapy may be a risk factor for the emergence of INH resistance in latent TB. 1,3

 Bonus Pearl: Did you know that INH treatment of latent TB in adults is 60-80% protective when given for 6 months, and 90% protective when given for 9 months? 4

References

  1. Ford CB, Lin PL, Chase M, et al . Use of whole genome sequencing to estimate the mutation rate of Mycobacterium tuberculosis during latent infection. Nat Genet. 2011;43:482-86. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3101871/
  2. Gideon HP, Flynn JL. Latent tuberculosis: what the host “sees”? Immunol Res 2011;50:202-12. https://www.ncbi.nlm.nih.gov/pubmed/21717066
  3. Balcells ME, Thomas SL, Faussett PG, et al. Isoniazid preventive therapy and risk for resistant tuberculosis. Emerg Infect Dis 2006;12:744-51. https://www.ncbi.nlm.nih.gov/pubmed/16704830
  4. Piccini P, Chiappini E, Tortoli E, et al. Clinical peculiarities of tuberculosis. BMC Infect Dis 2014; 14 (Suppl 1):S4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4015485/

 

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Why is latent tuberculosis usually treated with one antibiotic while active tuberculosis is treated with 2 or more drugs?

How is prealbumin related to albumin?

Aside from being synthesized in the liver and serving as a transport protein in the blood, prealbumin (PA) doesn’t really have much in common with albumin. More specifically, PA is not derived from albumin and, in fact, the two proteins are structurally distinct from each other!

So where does PA get its name? PA is the original name for transthyretin (TTR), a transport protein that primarily carries thyroxine (T4) and a protein bound to retinol (vitamin A). The name arose because TTR migrated faster than albumin on gel electrophoresis of human serum.1

Because of its much shorter serum half-life compared to that of albumin ( ~2 days vs ~20 days),2 PA is more sensitive to recent changes in protein synthesis and more accurately reflects recent dietary intake (not necessarily overall nutritional status) than albumin. 3

But, just like albumin, PA may represent a negative acute phase reactant, as its synthesis drops during inflammatory states in favor of acute phase reactants such as C-reactive protein. 4 So be cautious about interpreting low PA levels in patients with active infection, inflammation or trauma.

 

Reference

  1. Socolow EL, Woeber KA, Purdy RH, et al. Preparation of I-131-labeled human serum prealbumin and its metabolism in normal and sick patients. J. Clin Invest 1965; 44: 1600-1609. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC292644/
  2. Oppenheimer JH, Surks MI, Bernstein G, and Smith JC. Metabolism of Iodine-131-labeled Thyroxine-Binding Prealbumin in Man. Science 1965; 149: 748-750. https://www.ncbi.nlm.nih.gov/pubmed/14330531
  3. Ingenbleek Y, Young VR. Significance of prealbumin in protein metabolism. Clin Chem Lab Med 2002; 40: 1281-1291. https://www.ncbi.nlm.nih.gov/pubmed/12553432
  4. Shenkin A. Serum prealbumin: is it a marker of nutritional status or of risk of malnutrition? Clin Chem 2006;52:2177 – 2179. http://clinchem.aaccjnls.org/content/52/12/2177

 

Contributed by Colin Fadzen, Medical Student, Harvard Medical School, Boston, MA.

 

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How is prealbumin related to albumin?

My patient with COPD exacerbation on corticosteroids has an elevated white blood cell and neutrophil count. How can I tell if his elevated neutrophil count is caused by the corticosteroids or an acute infection?

The most helpful lab data favoring corticosteroid-induced granulocytosis (CIG) is the absence of a shift to the left in the peripheral WBC (ie, no more than 6% band forms) and toxic granulation.1 Although the total WBC itself is less helpful, experimental studies have reported a mean maximum neutrophil counts 2.4 times the base line after IV injection of hydrocortisone (200 mg) 2, and a mean increase of 4,000 neutrophils/mm3 after prednisone (20-80 mg). 3

Several possible mechanisms for CIG revolving around altered neutrophil characteristics and dynamics have been proposed4, including

  • Reduced egress from blood into tissues
  • Demargination from vascular endothelial surfaces
  • Delayed apoptosis
  • Enhanced release from the bone marrow.

An experimental animal study reported that only 10% of CIG is related to bone marrow release of neutrophils with the rest related to demargination (61%) and reduced egress from blood or delayed apoptosis (29%).4 This study may explain why high percentage of band forms would not be expected in CIG.

References

  1. Shoenfeld Y, Gurewich Y, Gallant LA, et al. Prednisone-induced leukocytosis: influence of dosage, method, and duration of administration on the degree of leukocytosis. Am J Med 1981;71:773-78. Link
  2. Bishop CR, Athens JW, Boggs DR, et al. Leukokinetic studies: A non-steady-state kinetic evaluation of the mechanism of cortisone-induced granulocytosis. J Clin Invest 1986;47:249-60. https://www.ncbi.nlm.nih.gov/pubmed/5638121
  3. Dale DC, Fauci AS, Guerry DuPont, et al. Comparison of agents producing a neutrophilic leukocytosis in man. J Clin Invest 1975;56:808-13. PDF
  4. Nakagawa M, Terashma T, D’yachkova YD, et al. Glucocorticoid-induced granulocytosis: Contribution of marrow release and demargination of intravascular granulocytes. Circulation 1998;98:2307-13. PDF

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My patient with COPD exacerbation on corticosteroids has an elevated white blood cell and neutrophil count. How can I tell if his elevated neutrophil count is caused by the corticosteroids or an acute infection?