title: Thyroid dysfunction and anaemia in a large population-based study.
abstract: OBJECTIVE
  Anaemia and thyroid dysfunction are common and often co-occur. Current guidelines recommend the assessment of thyroid function in the work-up of anaemia, although evidence on this association is scarce.
  
  
  METHODS
  In the 'European Prospective Investigation of Cancer' (EPIC)-Norfolk population-based cohort, we aimed to examine the prevalence and type of anaemia (defined as haemoglobin <13 g/dl for men and <12 g/dl for women) according to different thyroid function groups.
  
  
  RESULTS
  The mean age of the 8791 participants was 59·4 (SD 9·1) years and 55·2% were women. Thyroid dysfunction was present in 437 (5·0%) and anaemia in 517 (5·9%) participants. After excluding 121 participants with three most common causes of anaemia (chronic kidney disease, inflammation, iron deficiency), anaemia was found in 4·7% of euthyroid participants. Compared with the euthyroid group, the prevalence of anaemia was significantly higher in overt hyperthyroidism (14·6%, P < 0·01), higher with borderline significance in overt hypothyroidism (7·7%, P = 0·05) and not increased in subclinical thyroid dysfunction (5·0% in subclinical hypothyroidism, 3·3% in subclinical hyperthyroidism). Anaemia associated with thyroid dysfunction was mainly normocytic (94·0%), and rarely macrocytic (6·0%).
  
  
  CONCLUSIONS
  The prevalence of anaemia was higher in overt hyperthyroidism, but not increased in subclinical thyroid dysfunction. Systematic measurement of thyroid-stimulating hormone in anaemic patients is likely to be useful only after excluding common causes of anaemia.
authors.affiliation: Department of General Internal Medicine, Inselspital, University Hospital of Bern, Bern, Switzerland.
authors.forename: Khadija
authors.initials: K
authors.lastname: M'Rabet-Bensalah
authors.affiliation: Department of General Internal Medicine, Inselspital, University Hospital of Bern, Bern, Switzerland.
authors.forename: Carole E
authors.initials: CE
authors.lastname: Aubert
authors.affiliation: Department of Clinical Research, Clinical Trial Unit (CTU), University of Bern, Bern, Switzerland.
authors.forename: Michael
authors.initials: M
authors.lastname: Coslovsky
authors.affiliation: Service of Endocrinology, Diabetes and Metabolism, University Hospital of Lausanne, Lausanne, Switzerland.|University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: Tinh-Hai
authors.identifier: http://orcid.org/0000-0002-3243-1222
authors.initials: TH
authors.lastname: Collet
authors.affiliation: Department of General Internal Medicine, Inselspital, University Hospital of Bern, Bern, Switzerland.
authors.forename: Christine
authors.initials: C
authors.lastname: Baumgartner
authors.affiliation: Department of Public Health and Primary Care and Department of Clinical Chemistry and Laboratory Medicine, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Wendy P J
authors.initials: WP
authors.lastname: den Elzen
authors.affiliation: Department of Public Health and Primary Care, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: Robert
authors.initials: R
authors.lastname: Luben
authors.affiliation: Department of Clinical Research, Clinical Trial Unit (CTU), University of Bern, Bern, Switzerland.|University Clinic of Hematology and Central Hematology Laboratory, Inselspital, University Hospital of Bern, Bern, Switzerland.
authors.forename: Anne
authors.initials: A
authors.lastname: Angelillo-Scherrer
authors.affiliation: Department of General Internal Medicine, Inselspital, University Hospital of Bern, Bern, Switzerland.
authors.forename: Drahomir
authors.initials: D
authors.lastname: Aujesky
authors.affiliation: Department of Public Health and Primary Care, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: Kay-Tee
authors.initials: KT
authors.lastname: Khaw
authors.affiliation: Department of General Internal Medicine, Inselspital, University Hospital of Bern, Bern, Switzerland.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Rodondi
mesh_terms: D000368:Aged; D000740:Anemia / Q000175:diagnosis* / Q000453:epidemiology; D015897:Comorbidity; D004909:Erythrocyte Indices; D005060:Europe / Q000453:epidemiology; D005260:Female; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D006980:Hyperthyroidism / Q000097:blood / Q000453:epidemiology; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance / Q000379:methods*; D015995:Prevalence; D011446:Prospective Studies; D013961:Thyroid Gland / Q000503:physiopathology*; D013963:Thyroid Hormones / Q000097:blood
chemical_list: D006454:Hemoglobins; D013963:Thyroid Hormones