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Response to Letter to the Editor: “Ferritin deficiency may deteriorate the symptoms of Restless Legs Syndrome”
ARTICLE IN PRESS Sleep Medicine ■■ (2015) ■■
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Sleep Medicine j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e / s l e e p
Letter to the Editor Response to Letter to the Editor: “Ferritin deficiency may deteriorate the symptoms of Restless Legs Syndrome” To the Editor: We appreciate Drs. Tasdemir and Oz’s interest in our paper, “Restless legs syndrome and central nervous system gammaaminobutyric acid: preliminary associations with periodic limb movements in sleep and restless leg syndrome symptom severity,” published in Sleep Medicine [1]. We did not obtain iron indices in the subjects of that neuroimaging study. Central nervous system iron may certainly be essential to the pathophysiology of both primary and secondary RLS [2]. However, we know of no evidence that directly implicates CNS or serum iron in GABA, glutamate or NAA levels in patients with RLS. For this reason, we did not obtain serum iron measurements in our RLS subjects. Nevertheless, it is possible that iron deficiency plays a role in the neurometabolite measurements we observed in that study and that we may have had better insights into our data if we had used iron measures as covariates in that analysis.
References [1] Winkelman JW, Schoerning L, Platt S, et al. Restless legs syndrome and central nervous system gamma-aminobutyric acid: preliminary associations with periodic limb movements in sleep and restless leg syndrome symptom severity. Sleep Med 2014;15:1225–30. [2] Earley CJ, Connor J, Garcia-Borreguero D, et al. Altered brain iron homeostasis and dopaminergic function in Restless Legs Syndrome (Willis-Ekbom Disease). Sleep Med 2014;15:1288–301.
John W. Winkelman * Departments of Psychiatry and Neurology, Massachusetts General Hospital, 1 Bowdoin Square, Boston, MA 02114, USA * Address: Departments of Psychiatry and Neurology, Massachusetts General Hospital, 1 Bowdoin Square, Boston, MA 02114, USA. Tel.: +1 617 643 9101; fax: +1 617 643 6050. E-mail address: [email protected] Available online
Conflict of interest The ICMJE Uniform Disclosure Form for Potential Conflicts of Interest associated with this article can be viewed by clicking on the following link: http://dx.doi.org/10.1016/j.sleep.2015.09.012.
http://dx.doi.org/10.1016/j.sleep.2015.09.012 1389-9457/© 2015 Elsevier B.V. All rights reserved.
Please cite this article in press as: John W. Winkelman, Response to Letter to the Editor: “Ferritin deficiency may deteriorate the symptoms of Restless Legs Syndrome”, Sleep Medicine (2015), doi: 10.1016/j.sleep.2015.09.012
Contents lists available at ScienceDirect
Sleep Medicine j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e / s l e e p
Letter to the Editor Response to Letter to the Editor: “Ferritin deficiency may deteriorate the symptoms of Restless Legs Syndrome” To the Editor: We appreciate Drs. Tasdemir and Oz’s interest in our paper, “Restless legs syndrome and central nervous system gammaaminobutyric acid: preliminary associations with periodic limb movements in sleep and restless leg syndrome symptom severity,” published in Sleep Medicine [1]. We did not obtain iron indices in the subjects of that neuroimaging study. Central nervous system iron may certainly be essential to the pathophysiology of both primary and secondary RLS [2]. However, we know of no evidence that directly implicates CNS or serum iron in GABA, glutamate or NAA levels in patients with RLS. For this reason, we did not obtain serum iron measurements in our RLS subjects. Nevertheless, it is possible that iron deficiency plays a role in the neurometabolite measurements we observed in that study and that we may have had better insights into our data if we had used iron measures as covariates in that analysis.
References [1] Winkelman JW, Schoerning L, Platt S, et al. Restless legs syndrome and central nervous system gamma-aminobutyric acid: preliminary associations with periodic limb movements in sleep and restless leg syndrome symptom severity. Sleep Med 2014;15:1225–30. [2] Earley CJ, Connor J, Garcia-Borreguero D, et al. Altered brain iron homeostasis and dopaminergic function in Restless Legs Syndrome (Willis-Ekbom Disease). Sleep Med 2014;15:1288–301.
John W. Winkelman * Departments of Psychiatry and Neurology, Massachusetts General Hospital, 1 Bowdoin Square, Boston, MA 02114, USA * Address: Departments of Psychiatry and Neurology, Massachusetts General Hospital, 1 Bowdoin Square, Boston, MA 02114, USA. Tel.: +1 617 643 9101; fax: +1 617 643 6050. E-mail address: [email protected] Available online
Conflict of interest The ICMJE Uniform Disclosure Form for Potential Conflicts of Interest associated with this article can be viewed by clicking on the following link: http://dx.doi.org/10.1016/j.sleep.2015.09.012.
http://dx.doi.org/10.1016/j.sleep.2015.09.012 1389-9457/© 2015 Elsevier B.V. All rights reserved.
Please cite this article in press as: John W. Winkelman, Response to Letter to the Editor: “Ferritin deficiency may deteriorate the symptoms of Restless Legs Syndrome”, Sleep Medicine (2015), doi: 10.1016/j.sleep.2015.09.012