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

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.

 

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 has been admitted to the hospital several times this year with bacterial infections. How does cirrhosis increase susceptibility to infections?

Bacterial infections are a common cause of morbidity and mortality in patients with cirrhosis, affecting about 30% of such patients either at admission or during their hospitalization, with an attendant risk of mortality that is twice that of individuals without cirrhosis1.

Two major mechanisms may account for the observed immune dysfunction in cirrhosis: 1. Compromise of the immune surveillance function of the liver itself through damage of the reticulo-endothelial system (RES) and reduced synthesis of innate immunity proteins and pattern recognition receptors (PRRs); and 2. Dysfunctions of circulating and intestinal population of immune cells2.

Damage to the RES in cirrhosis leads to portal-system shunting, loss/damage of Kupffer cells (specialized hepatic macrophages) and sinusoidal capillarization, all hindering blood-borne pathogen clearance. Cirrhosis is also associated with a defect in hepatic protein synthesis, including complement components, decreased PRRs and acute phase reactants (eg C-reactive protein), which may in turn lead to the impairment of the innate immunity and bacterial opsonization.

Cirrhosis can also cause reduction in the number and function of neutrophils (eg, decreased phagocytosis and chemotaxis), B, T, and NK lymphocytes, and decreased in bacterial phagocytosis by monocytes. In addition, damage to the gut-associated lymphoid tissue (eg Peyer’s patches and mesenteric lymph nodes) may facilitate bacterial translocation.

References

  1. Pieri G, Agarwal B, Burroughs AK. C-reactive protein and bacterial infections in cirrhosis. Ann Gastroenterol 2014;27:113-120. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3982625/pdf/AnnGastroenterol-27-113.pdf
  2. Albillos A, Lario M, Alvarez-Mon M. Cirrhosis-associated immune dysfunction: distinctive features and clinical relevance. J Hepatol 2014;61:1385-1396. http://www.journal-of-hepatology.eu/article/S0168-8278(14)00549-2/pdf

 

My patient with cirrhosis has been admitted to the hospital several times this year with bacterial infections. How does cirrhosis increase susceptibility to infections?

My middle age patient complains of night sweats for several months, but she has had no weight loss and does not appear ill. What could I be missing?

Night sweats (NS) is a common patient complaint, affecting about a third of hospitalized patients on medical wards1.  Despite its long list of potential causes, direct relationship between the often- cited conditions and NS is usually unclear2, its cause may remain elusive In about a third to half of cases in the primary care setting, and its prognosis, at least in those >65 y of age, does not appear to be unfavorable 2,3.

Selected commonly and less frequently cited conditions associated with NS are listed (Table)2-9.  Although tuberculosis is one of the first conditions we think of when faced with a patient with NS, it should be emphasized that NS is not common in this disease (unless advanced) and is rare among hospitalized patients as a cause of their NS1,9.

In one of the larger study of adult patients seen in primary care setting, 23% reported pure NS and an additional 18% reported night and day sweats5; the prevalence of NS in both men and women was highest in 41-55 y age group. In multivariate analyses, factors associated with pure NS in women were hot flashes and panic attacks; in men, sleep disorders. 

Table. Selected causes of night sweats

Commonly cited Less frequently cited
Neoplastic/hematologic (eg, lymphoma, leukemia, myelofibrosis)

Infections (eg, HIV, tuberculosis, endocarditis)

Endocrine (eg, ovarian failure, hyperthyroidism, orchiectomy, carcinoid tumor, diabetes mellitus [nocturnal hypoglycemia], pheochromocytoma)

Rheumatologic (eg, giant cell arteritis)

Gastroesophageal reflux disease

B-12 deficiency

Pulmonary embolism

Drugs (eg, anti-depressants, SSRIs, donepezil [Aricept], tacatuzumab)

Sleep disturbances (eg, obstructive sleep apnea)

Panic attacks/anxiety disorder

Obesity

Hemachromatosis

Diabetes insipidus

References

  1. Lea MJ, Aber RC, Descriptive epidemiology of night sweats upon admission to a university hospital. South Med J 1985;78:1065-67.
  2. Mold JW, Holtzclaw BJ, McCarthy L. Night sweats: A systematic review of the literature. J Am Board Fam Med 2012; 25-878-893.
  3. Mold JW, Lawler F. The prognostic implications of night sweats in two cohorts of older patients. J Am Board Fam Med 2010;23:97-103.
  4. Mold JW, Holtzclaw BJ. Selective serotonin reuptake inhibitors and night sweats in a primary care population. Drugs-Real World Outcomes 2015;2:29-33.
  5. Mold JW, Mathew MK, Belgore S, et al. Prevalence of night sweats in primary care patients: An OKPRN and TAFP-Net collaborative study. J Fam Pract 2002; 31:452-56.
  6. Feher A, Muhsin SA, Maw AM. Night sweats as a prominent symptom of a patient presenting with pulmonary embolism. Case reports in Pulmonology 2015. http://dx.doi.org/10.1155/2015/841272
  7. Rehman HU. Vitamin B12 deficiency causing night sweats. Scottish Med J 2014;59:e8-11.
  8. Murday HK, Rusli FD, Blandy C, et al. Night sweats: it may be hemochromatosis. Climacteric 2016;19:406-8.
  9. Fred HL. Night sweats. Hosp Pract 1993 (Aug 15):88.
My middle age patient complains of night sweats for several months, but she has had no weight loss and does not appear ill. What could I be missing?

How should I interpret a positive urine pneumococcal antigen when my suspicion for pneumococcal disease is very low?

The popular urine pneumococcal antigen (UPA) (based on the C-polysaccharide of Streptococcus pneumoniae cell wall) has been a valuable diagnostic tool in diagnosing invasive pneumococcal infections, but may be associated with up to nearly 10% rate of false-positivity in hospitalized patients1.  Three factors have often been cited as the  cause of false-positive UPA results: a. Nasopharyngeal carriage; b.Prior invasive pneumococcal infection and;  c. Pneumococcal vaccination.

Among adults with nasopharyngeal carriage of S. pneumoniae, particularly those with HIV infection, 12-17% of positive UPA tests may be false-positive1. In patients with recent invasive pneumococcal disease, UAP may remain positive in over 50% of patient at 1 month and about 5% at 6 months1,2.

Among persons receiving the 23-valent polysaccharide pneumococcal vaccine (PPV), over 20% may have a positive UPA up to 30 hours following immunization, some potentially longer1.  In fact, the manufacturer of UPA assay recommends that UPA not be obtained within 5 days of receiving PPV. There is reason to believe that conjugated pneumococcal vaccine may be associated with the same phenomenon3.

So in a hospitalized patient with low suspicion for pneumococcal disease but a positive UAP, it would be wise to first exclude the possibility of PPV administration earlier during hospitalization before the sample was obtained1,4.

 

References

  1. Ryscavage PA, Noskin GA, Bobb A, et al. Incidence and impact of false-positive urine pneumococcal antigen testing in hospitalized patients. S Med J 2011;104:293-97.
  2. Andre F, Prat C, Ruiz-Manzano J, et al. Persistence of Streptococcus pneumoniae urinary antigen excretion after pneumococcal pneumonia. Eur J Clin Microbiol Infect Dis 2009;28:197-201.
  3. Navarro D, Garcia-Maset Leonor, Gimeno C, et al. Performance of the Binax NOW Streptococcus pneumoniae urinary assay for diagnosis of pneumonia in children with underlying pulmonary diseases in the absence of acute pneumococcal infection. J Clin Microbiol 2004; 42: 4853-55.
  4. Song JY, Eun BW, Nahm MH. Diagnosis of pneumococcal pneumonia: current pitfalls and the way forward. Infect Chemother 2013;45:351-66.

 

How should I interpret a positive urine pneumococcal antigen when my suspicion for pneumococcal disease is very low?

My patient with acute onset headache, photophobia, and neck stiffness does not have CSF pleocytosis. Could she still have meningitis?

Although the clinical diagnosis of meningitis is often supported by the presence of abnormal number of WBCs in the CSF (AKA pleocytosis), meningitis may be present despite its absence. Among viral causes of meningitis in adults, enteroviruses are associated with lower CSF WBC count compared to herpes simplex and varicella zoster, with some patients (~10%) having 0-2 WBC’s/mm31,2.  Of interest, among children, parechovirus (formerly echovirus 22 and 23) meningitis is characterized by normal CSF findings3.

Though uncommon, bacterial meningitis without CSF pleocytosis has been reported among non-neutropenic adults,  involving a variety of pathogens such as Neisseria meningitidis, Streptococcus pneumoniae, Hemophilus influenzae, Listeria monocytogenes, E. coli, and Proteus mirabilis4. Cryptococcal meninigitis may also be associated with normal CSF profile in 25% of patients with HIV infection5.

Thus, despite the absence of CSF pleocytosis, appropriate microbiological studies may still be necessary in some patients suspected of meningitis.

 

References

  1. Ihekwaba UK, Kudesia G, McKendrick MW. Clinical features of viral meningitis in adult:significant differences in cerebrospinal fluid findings among herpes simplex
  2. Dawood N, Desjobert E, Lumley J et al. Confirmed viral meningitis with normal CSF findings. BMJ Case Rep 2014. Doi:10.1136/bcr-2014-203733.
  3. Wolthers KC, Benschop KSM, Schinkel J, et al. Human parechovirus as an important viral cause of sepsis like illness and meningitis in young children. Clin Infect Dis 2008;47:358-63.
  4. Hase R, Hosokawa N, Yaegashi M, et al. Bacterial meningitis in the absence of cerebrospinal fluid pleocytosis: A case report and review of the literature. Can J Infect Dis Med Microbiol 2014;25:249:51.
  5. Darras-Joly C, Chevret S, Wolff M, et al. Cryptococcus neoformans infection in France: epidemiologic features of and early prognostic parameters for 76 patients who were infected with human immunodeficiency virus. Clin Infect Dis 1996;23:369-76.
My patient with acute onset headache, photophobia, and neck stiffness does not have CSF pleocytosis. Could she still have meningitis?

My patient has a sacral decubitus ulcer that can be probed to the bone. Should I assume she has osteomyelitis?

When dealing with pressure sores, there is no definitive way of making a diagnosis of osteomyelitis short of a biopsy of the involved bone1.  In fact, only about a third of stage IV pressure ulcers (those extending to the bone) may be associated with osteomyelitis2. In a study of pressure sores related to spinal cord injury or cerebrovascular accident, the clinical judgement of physicians with respect to the presence of osteomyelitis was accurate in only 56% of patients.  Only 3 of 21 patients with exposed bone had a diagnosis of osteomyelitis confirmed on biopsy3.

The “Probe to the Bone” bedside procedure has been studied primarily in diabetic foot infections with a recent systematic review reporting pooled sensitivity and specificity of 0.87 (95% confidence interval [CI], .75-.93) and 0.83 (95% CI, .65-.93), respectively4. Its performance in non-diabetic patients or those without a foot infection needs further study.

So in our patient, we should not assume a diagnosis of osteomyelitis; a bone biopsy is necessary for a definitive diagnosis.

References

  1. Larson DL, Gilstrap J, Simonelic K, et al. Is there a simple, definitive, and cost-effective way to diagnose osteomyelitis in the pressure ulcer patient? Plast Reconstr Surg 2011; 127:67
  2. Bodavula P, Liang SY, Wu J et al. Pressure ulcer-related pelvic osteomyelitis: a neglected disease? Open Forum Infect Dis 2015. DOI:10.1093/ofid/ofv112.
  3. Darouiche RO, Landon GC, Klima M et al. Osteomyelitis associated with pressure sores. Arch Intern Med 1994;154:753-58.
  4. Lam K, van Asten SA, Nguyen T, et al. Diagnostic accuracy of probe to bone to detect osteomyelitis in the diabetic foot: a systematic review. Clin Infect Dis 2016;63:944-8.
My patient has a sacral decubitus ulcer that can be probed to the bone. Should I assume she has osteomyelitis?

Is intermittent urethral catheterization preferred over continuous indwelling catheters for short-term management of urinary retention in my hospitalized patient?

For continuous urethral catheterization (CUC), the estimated daily risk of acquisition of bacteriuria is 3% to 8%1-3.  For intermittent urethral catheterization (IUC), the incidence of bacteriuria is 1% to 3% per insertion4. The Infectious Diseases Society of America recommends that IUC should be considered as an alternative to short-term CUC to reduce catheter-associated bacteriuria or UTI based on “poor evidence”  (Category C) and, as relates to symptomatic UTIs, without properly designed randomized-controlled studies2.  

A Cochrane systematic review of CUC vs IUC in hospitalized patients failed to find any significant differences between the 2 interventions as relates to the rates of symptomatic UTI and asymptomatic bacteriuria in hospitalized patients requiring short-term catheterization5.   Of interest, nearly 3 times as many people developed acute urinary retention with IUC compared to CUC in this study (16% vs 45%, respectively, RR 0.45, 95% CI 0.22-0.91).  

In short, despite its theoretical advantage in reducing the risk of UTIs due to lack of a constant presence of a catheter, solid data to support preference of ICU over CUC in short-term management of urinary retention in hospitalized patients is still lacking.

References

  1. Lo, Nicolle LE, Coffin SE, et al. Strategies to prevent catheter-associated urinary tract infections in acute care hospitals: 2014 update. Infect Control Hosp Epidemiol 2014;35:464-78.
  2. Hooton TM, Bradley SF, Cardenas DD, et al. Diagnosis, prevention, and treatment of catheter-associated urinary tract infection in adults: 2009 International Clinical Practice Guidelines from the Infectious Diseases Society of America. Clin Infect Dis 2010;50:625-663.
  3. Kunin CM, McCormack RC. Prevention of catheter-induced urinary-tract infections by sterile closed drainage. N Engl J Med 1966;274:1155-61.
  4. Saint S, Lipsky BA. Preventing catheter-related bacteriuria: Should we? Can we? How? Arch Intern Med 1999;159:800-808.
  5. Kidd EA, Stewart F, Kassis NC, et al. Urethral (indwelling or intermittent) or suprapubic routes for short-term catheterization in hospitalized adults (review). Cochrane Database of Systematic Reviews 2015; Issue 12. Art No. :CD004203.

 

 

 

Is intermittent urethral catheterization preferred over continuous indwelling catheters for short-term management of urinary retention in my hospitalized patient?