What is the evidence for iron deficiency causing pica?

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).

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.
  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.
  3. Von Bonsdorff B. Pica: a hypothesis.. British J Haematol 1977;35:476-477.

 

Contributed by S.J. Lee, Harvard Medical Student

What is the evidence for iron deficiency causing pica?

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

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?

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! This test may be positive in as many as 94% of patients within a week of having a stroke (1).  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 (2). Interestingly, if one arm drifts upward this suggests a lesions outside the CST, possibly a cerebellar or parietal lesion, which may be equally concerning.

 

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.
  2. Campbell, WW. In DeJong’s The Neurologic Examination-6th Ed, p389-392, 2005. Lippincott Williams&Wilkins, Philadelphia.

 

 

 

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

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