Response to the letter: Red cell distribution width in subclinical hypothyroidism

Distribuição dos glóbulos vermelhos ampliada no hipotiroidismo subclínico

Hea Min Yu Kang Seo Park Jae Min Lee About the authors

We read the paper by Sevket BALTA and cols. and thanks for your interest in our study entitled “Red Cell Distribution Width in Subclinical Hypothyroidism” (1Yu HM, Park KS, Lee JM. The value of red blood cell distribution width in subclinical hypothyroidism. Arq Bras Endocrinol Metabol. 2014;58(1):30-6.). As we mentioned in the discussion part, the RDW can be affected by some disease conditions such as recent blood transfusion, renal dysfunction, hepatic dysfunction, anemia related nutritional deficiencies (i.e. iron, vitamin B12, and folic acid), bone marrow dysfunction, inflammatory diseases, chronic or acute systemic inflammation (2Balta S, Demirkol S, Hatipoglu M, Ardic S, Arslan Z, Celik T. Red cell distribution width is a predictor of mortality in patients with severe sepsis and septic shock. Am J Emerg Med. 2013;31(6):989-90.

Demirkol S, Balta S, Cakar M, Unlu M, Arslan Z, Kucuk U. Red cell distribution width: a novel inflammatory marker in clinical practice. Cardiol J. 2013;20(2):209.

Ferrucci L, Guralnik JM, Bandinelli S, Semba RD, Lauretani F, Corsi A, et al. Unexplained anaemia in older persons is characterised by low erythropoietin and low levels of pro-inflammatory markers. Br J Haematol. 2007;136(6):849-55.
-5Kiefer CR, Snyder LM. Oxidation and erythrocyte senescence. Curr Opin Hematol. 2000;7(2):113-6.) and some medications (6Fici F, Celik T, Balta S, Iyisoy A, Unlu M, Demitkol S, et al. Comparative effects of nebivolol and metoprolol on red cell distribution width and neutrophil/lymphocyte ratio in patients with newly diagnosed essential hypertension. J Cardiovasc Pharmacol. 2013;62(4):388-93.) is already well known. And this point could be one of the major limitations of our paper. So, we tried to gather other multiple potential confounding factors as much as possible and to adjust confounding factors. And the reason what the participants comprised healthy subjects with no known systemic diseases and who were not taking any medication that may affect thyroid function, and were not pregnant or within the first year of the postpartum period is to rule out the confounding factors. Because of this aspect your paper pointed out, in fact, more investigations and prospective studies are needed to clarify the relations between RDW and subclinical hypothyroidism before application in the clinical field.

And we, authors used the formula developed and validated in the Modification of Diet in Renal Disease (MDRD) to estimate glomerular filtration rate (GFR). As your paper mentioned, according to the current trends, the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation replace the Modification of Diet in Renal Disease (MDRD) Study equation (7Herzog CA. Kidney disease in cardiology. Nephrol Dial Transplant. 2009;24(1):34-7.

McFarlane SI, McCullough PA, Sowers JR, Soe K, Chen SC, Li S, et al. Comparison of the CKD Epidemiology Collaboration (CKD-EPI) and Modification of Diet in Renal Disease (MDRD) study equations: prevalence of and risk factors for diabetes mellitus in CKD in the Kidney Early Evaluation Program (KEEP). Am J Kidney Dis. 2011;57(3 Suppl 2):S24-31.
-9Stevens LA, Li S, Kurella Tamura M, Chen SC, Vassalotti JA, Norris KC, et al. Comparison of the CKD Epidemiology Collaboration (CKD-EPI) and Modification of Diet in Renal Disease (MDRD) study equations: risk factors for and complications of CKD and mortality in the Kidney Early Evaluation Program (KEEP). Am J Kidney Dis. 2011;57(3 Suppl 2):S9-16.). We all agree with your this opinion and can afford to accept your advice. Although we used the MDRD study equation in our paper as usual, in the further study we would plan to use the CKD-EPI equation instead.

When it comes to the additional final question, considering laboratory system of our hospital, we can ensure that analysis of blood sample is not delayed enough to cause abnormal results in RDW measurements.

In addition, because we also have confidence that relationship between inflammatory factors and subclinical hypothyroidism is exist (4Ferrucci L, Guralnik JM, Bandinelli S, Semba RD, Lauretani F, Corsi A, et al. Unexplained anaemia in older persons is characterised by low erythropoietin and low levels of pro-inflammatory markers. Br J Haematol. 2007;136(6):849-55.,1010 Demirkol S, Balta S, Unlu M, Yuksel UC, Celik T, Arslan Z, et al. Evaluation of the mean platelet volume in patients with cardiac syndrome X. Clinics. 2012;67(9):1019-22.,1111 Patel KV, Ferrucci L, Ershler WB, Longo DL, Guralnik JM. Red blood cell distribution width and the risk of death in middle-aged and older adults. Arch Intern Med. 2009;169(5):515-23.), we guess that the studies deal with inflammatory factors such as RDW, mean platelet volume, neutrophil lymphocyte ratio, CRP, and so on, would have value and should be keep on investigating.

REFERENCES

  • 1
    Yu HM, Park KS, Lee JM. The value of red blood cell distribution width in subclinical hypothyroidism. Arq Bras Endocrinol Metabol. 2014;58(1):30-6.
  • 2
    Balta S, Demirkol S, Hatipoglu M, Ardic S, Arslan Z, Celik T. Red cell distribution width is a predictor of mortality in patients with severe sepsis and septic shock. Am J Emerg Med. 2013;31(6):989-90.
  • 3
    Demirkol S, Balta S, Cakar M, Unlu M, Arslan Z, Kucuk U. Red cell distribution width: a novel inflammatory marker in clinical practice. Cardiol J. 2013;20(2):209.
  • 4
    Ferrucci L, Guralnik JM, Bandinelli S, Semba RD, Lauretani F, Corsi A, et al. Unexplained anaemia in older persons is characterised by low erythropoietin and low levels of pro-inflammatory markers. Br J Haematol. 2007;136(6):849-55.
  • 5
    Kiefer CR, Snyder LM. Oxidation and erythrocyte senescence. Curr Opin Hematol. 2000;7(2):113-6.
  • 6
    Fici F, Celik T, Balta S, Iyisoy A, Unlu M, Demitkol S, et al. Comparative effects of nebivolol and metoprolol on red cell distribution width and neutrophil/lymphocyte ratio in patients with newly diagnosed essential hypertension. J Cardiovasc Pharmacol. 2013;62(4):388-93.
  • 7
    Herzog CA. Kidney disease in cardiology. Nephrol Dial Transplant. 2009;24(1):34-7.
  • 8
    McFarlane SI, McCullough PA, Sowers JR, Soe K, Chen SC, Li S, et al. Comparison of the CKD Epidemiology Collaboration (CKD-EPI) and Modification of Diet in Renal Disease (MDRD) study equations: prevalence of and risk factors for diabetes mellitus in CKD in the Kidney Early Evaluation Program (KEEP). Am J Kidney Dis. 2011;57(3 Suppl 2):S24-31.
  • 9
    Stevens LA, Li S, Kurella Tamura M, Chen SC, Vassalotti JA, Norris KC, et al. Comparison of the CKD Epidemiology Collaboration (CKD-EPI) and Modification of Diet in Renal Disease (MDRD) study equations: risk factors for and complications of CKD and mortality in the Kidney Early Evaluation Program (KEEP). Am J Kidney Dis. 2011;57(3 Suppl 2):S9-16.
  • 10
    Demirkol S, Balta S, Unlu M, Yuksel UC, Celik T, Arslan Z, et al. Evaluation of the mean platelet volume in patients with cardiac syndrome X. Clinics. 2012;67(9):1019-22.
  • 11
    Patel KV, Ferrucci L, Ershler WB, Longo DL, Guralnik JM. Red blood cell distribution width and the risk of death in middle-aged and older adults. Arch Intern Med. 2009;169(5):515-23.

Publication Dates

  • Publication in this collection
    Dec 2014

History

  • Received
    23 June 2014
  • Accepted
    7 Sept 2014
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