title: Effects of thyroid status on glycated hemoglobin.
abstract: BACKGROUND
  Glycated hemoglobin (HbA1c) can be altered in different conditions. We hypothesize that HbA1c levels may change due to altered thyroid status, possibly due to changes in red blood cell (RBC) turnover.
  
  
  OBJECTIVE
  The objective of this study was to determine the effects of altered thyroid status on HbA1c levels in individuals without diabetes, with overt hyper- and hypo-thyroidism, and if present, whether such changes in HbA1c are reversed after achieving euthyroid state.
  
  
  METHODS
  Euglycemic individuals with overt hypo- or hyper-thyroidism were selected. Age- and sex-matched controls were recruited. Baseline HbA1c and reticulocyte counts (for estimation of RBC turnover) were estimated in all the patients and compared. Thereafter, stable euthyroidism was achieved in a randomly selected subgroup and HbA1c and reticulocyte count was reassessed. HbA1c values and reticulocyte counts were compared with baseline in both the groups.
  
  
  RESULTS
  Hb A1c in patients initially selected was found to be significantly higher in hypothyroid group. HbA1c values in hyperthyroid patients were not significantly different from controls. HbA1c reduction and rise in reticulocyte count were significant in hypothyroid group following treatment without significant change in glucose level. Hb A1c did not change significantly following treatment in hyperthyroid group. The reticulocyte count, however, decreased significantly.
  
  
  CONCLUSIONS
  Baseline HbA1c levels were found to be significantly higher in hypothyroid patients, which reduced significantly after achievement of euthyroidism without any change in glucose levels. Significant baseline or posttreatment change was not observed in hyperthyroid patients. Our study suggests that we should be cautious while interpreting HbA1c data in patients with hypothyroidism.
authors.affiliation: Department of Endocrinology and Metabolism, IPGME and R and SSKM Hospital, Kolkata, West Bengal, India.
authors.forename: Rana
authors.initials: R
authors.lastname: Bhattacharjee
authors.affiliation: Department of Endocrinology and Metabolism, IPGME and R and SSKM Hospital, Kolkata, West Bengal, India.
authors.forename: Anubhav
authors.initials: A
authors.lastname: Thukral
authors.affiliation: Department of Endocrinology and Metabolism, IPGME and R and SSKM Hospital, Kolkata, West Bengal, India.
authors.forename: Partha Pratim
authors.initials: PP
authors.lastname: Chakraborty
authors.affiliation: Department of Endocrinology and Metabolism, IPGME and R and SSKM Hospital, Kolkata, West Bengal, India.
authors.forename: Ajitesh
authors.initials: A
authors.lastname: Roy
authors.affiliation: Department of Endocrinology and Metabolism, IPGME and R and SSKM Hospital, Kolkata, West Bengal, India.
authors.forename: Soumik
authors.initials: S
authors.lastname: Goswami
authors.affiliation: Department of Endocrinology and Metabolism, IPGME and R and SSKM Hospital, Kolkata, West Bengal, India.
authors.forename: Sujoy
authors.initials: S
authors.lastname: Ghosh
authors.affiliation: Department of Endocrinology and Metabolism, IPGME and R and SSKM Hospital, Kolkata, West Bengal, India.
authors.forename: Pradip
authors.initials: P
authors.lastname: Mukhopadhyay
authors.affiliation: Department of Endocrinology and Metabolism, IPGME and R and SSKM Hospital, Kolkata, West Bengal, India.
authors.forename: Satinath
authors.initials: S
authors.lastname: Mukhopadhyay
authors.affiliation: Department of Endocrinology and Metabolism, IPGME and R and SSKM Hospital, Kolkata, West Bengal, India.
authors.forename: Subhankar
authors.initials: S
authors.lastname: Chowdhury
keywords: Assay interpretation; HbA1c; thyroid function