Month: May 2016

What is the evidence for iron deficiency causing pica?

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

Pica refers to the compulsive craving and persistent consumption of substances not fit as food such as ice (pagophagia) and soil (geophagia). Several reports have implicated iron deficiency as a cause of pica, with resolution of symptoms following treatment of iron deficiency (1).

In a recent study involving blood donors , pica (particularly pagophagia) was nearly 3 times as likely among donors with iron deficiency  compared to iron-replete donors (11%  vs 4%, respectively, P<0.0001).  In the same study, donors with pica reported a marked reduction in their pica by day 5-8 of iron therapy. 

It has been suggested that cerebral tissue function may be adversely impacted by a deficiency in Fe-containing enzymes (e.g. cytochrome c reductase) resulting in behavioral disorders, such as hyperactivity and pica (2).  

Of interest, cats can be induced to swallow inedible objects when certain points in the hypothalamic area high in iron content are stimulated (3).

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References

 

  1. Bryant BJ, Yau YY, Arceo SM, et al. Ascertainment of iron deficiency and depletion in blood donors through screening questions for pica and restless legs syndrome. Transfusion 2013;53:1637-1644. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3691288
  2. Osman YM, Wali YA, Osman OM. Craving for ice and iron-deficiency anemia: a case series from Oman. Pediatric Hematol Oncol 2005; 22:127-131. https://www.ncbi.nlm.nih.gov/pubmed/15804997
  3. Von Bonsdorff B. Pica: a hypothesis.. British J Haematol 1977;35:476-477.  https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2141.1977.tb00611.x

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!

Contributed by S.J. Lee,  Medical Student, Harvard Medical School, Boston, MA

What is the evidence for iron deficiency causing pica?

Should rifampin be routinely included in the treatment of staphylococcal infections involving retained prosthetic joints?

FA Manian MD, MPH, , Leave a comment

Rifampin has excellent penetration of biofilms in vitro (1). According to the Infectious Disease Society of America (IDSA) guidelines, it should be used in combination with another anti-staphylococcal antibiotic in the treatment of staphylococcal prosthetic joint infections for 3-6 months following debridement of a retained prosthesis (level A1 recommendation) (2).

Although a small randomized-controlled trial between ciprofloxacin and ciprofloxacin-rifampin reported a dramatic 100% cure rate in patients treated with the combination regimen (vs 58% with ciprofloxacin alone) (3), its small sample size (n=24) with its high drop-out rate, beg for a larger study comparing a more conventional anti-staphylococcal drug regimen such as a beta-lactam or vancomycin with and without rifampin. In the meantime, be on the alert for rifampin-induced drug resistance, hepatotoxicity, and frequent CYP450 drug interactions (e.g. warfarin) when used in combination with other anti-staphylococcal drugs (1).

 

References

  1. Forrest GN, Tamura K. Rifampin combination therapy for nonmycobacterial infections. Clin Microbiol Rev. 2010;23(1):14-34.
  2. Osmon DR, Berbari EF, Berendt AR, et al. Diagnosis and management of prosthetic joint infection: clinical practice guidelines by the Infectious Diseases Society of America. Clin Infect Dis. 2013;56(1):e1-e25.
  3. Zimmerli W, Widmer AF, Blatter M, Frei R, Ochsner PE. Role of rifampin for treatment of orthopedic implant-related staphylococcal infections: a randomized controlled trial. Foreign-Body Infection (FBI) Study Group. JAMA. 1998;279(19):1537-1541.

 

Contributed by Sam Slavin, Harvard Medical Student, Boston, MA.

Should rifampin be routinely included in the treatment of staphylococcal infections involving retained prosthetic joints?

Which motor test may be the most useful maneuver when examining a patient suspected of having a stroke?

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

When limited by the number of motor tests that can be performed on a patient suspected of having a stroke, the pronator drift may be your best bet! The sensitivity of this test has varied from 22% to as high as 94% for patients within a week of having a stroke; it is highly specific, however (1,2).

 An advantage of this maneuver is that it can point to subtle lesions in the corticospinal tract (CST) often missed by formal strength testing.

To perform the test, ask the patient to hold his or her arms straight out in front with palms facing upwards and eyes closed for 20-30 seconds. Slight pronation of one hand and flexion of the elbow suggests mild drift. Additional downward drift of the entire arm may also be present with more severe deficits (3). Interestingly, if one arm drifts upward this suggests a lesions outside the CST, possibly a cerebellar or parietal lesion, which may be equally concerning.

 

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References

  1. Louis ED, King D, Sacco R, et al. Upper motor neuron signs in acute stroke: prevalence, interobserver reliability, and timing of initial examination. J Stroke Cerebrovasc Dis 1995;5:49-55. https://www.ncbi.nlm.nih.gov/pubmed/26486559 
  2. Anderson NE, Mason DF, Fink JN. Detection of focal cerebral hemisphere lesions using the neurological examination. J Neurol Neurosurg Psychiatry 2005;76:545-49. https://jnnp.bmj.com/content/jnnp/76/4/545.full.pdf 
  3. Campbell, WW. In DeJong’s The Neurologic Examination-6th Ed, p389-392, 2005. Lippincott Williams&Wilkins, Philadelphia.

 

Contributed in part by Alexis Roy, Harvard Medical Student, Boston, MA.

 

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. 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!

Which motor test may be the most useful maneuver when examining a patient suspected of having a stroke?