title: Shift of the TSH reference range with improved iodine supply in Northeast Germany.
abstract: OBJECTIVE
  Germany was iodine deficient until the mid-1990s when a nationwide iodine fortification program became effective. It is expected that after a longer period of sufficient iodine supply, median TSH values in the general population will shift to the right. Hence, the previous TSH reference range does not reflect the current TSH distribution in the general population of Germany. Thus, we aimed to establish a new reference range for serum TSH levels.
  
  
  METHODS
  We used data from the Study of Health in Pomerania TREND, a population-based study including 4420 individuals. The reference population consisted of 1596 individuals without diagnosed thyroid diseases or thyroid-related findings in ultrasound and serum analysis. Serum TSH levels were measured by an immunochemiluminescent procedure on a Siemens Dimension Vista.
  
  
  RESULTS
  The overall reference range for TSH was 0.49 mIU/l (95% CI=0.44; 0.53)-3.29 mIU/l (95% CI=3.08; 3.50). The lower reference limit differed significantly by sex, whereas the upper reference limit showed no significant difference between males and females. Age was significantly associated with the 2.5th TSH percentile in males but not in females, whereas age was significantly associated in males and females for the 97.5th TSH percentile.
  
  
  CONCLUSIONS
  We demonstrate a shift toward the right of the TSH reference range in comparison with data from the same study region 10 years earlier, which is likely due to the improved iodine supply of the study region. Our study indicates that TSH reference limits are dependent on past and current iodine supply of populations.
authors.affiliation: Institute for Community MedicineErnst Moritz Arndt University, University of Greifswald, Walther-Rathenau Straße 48, D-17475 Greifswald, GermanyInstitute of Clinical Chemistry and Laboratory MedicineUniversity of Greifswald, Greifswald, GermanyDZHK (German Center for Cardiovascular Research)Partner Site Greifswald, University of Greifswald, Greifswald, GermanyDepartamento de Ciências FarmacêuticasUniversidade Regional de Blumenau, Blumenau, Brazil till.ittermann@uni-greifswald.de.
authors.forename: Till
authors.initials: T
authors.lastname: Ittermann
authors.affiliation: Institute for Community MedicineErnst Moritz Arndt University, University of Greifswald, Walther-Rathenau Straße 48, D-17475 Greifswald, GermanyInstitute of Clinical Chemistry and Laboratory MedicineUniversity of Greifswald, Greifswald, GermanyDZHK (German Center for Cardiovascular Research)Partner Site Greifswald, University of Greifswald, Greifswald, GermanyDepartamento de Ciências FarmacêuticasUniversidade Regional de Blumenau, Blumenau, Brazil.
authors.forename: Rehman M
authors.initials: RM
authors.lastname: Khattak
authors.affiliation: Institute for Community MedicineErnst Moritz Arndt University, University of Greifswald, Walther-Rathenau Straße 48, D-17475 Greifswald, GermanyInstitute of Clinical Chemistry and Laboratory MedicineUniversity of Greifswald, Greifswald, GermanyDZHK (German Center for Cardiovascular Research)Partner Site Greifswald, University of Greifswald, Greifswald, GermanyDepartamento de Ciências FarmacêuticasUniversidade Regional de Blumenau, Blumenau, Brazil.
authors.forename: Matthias
authors.initials: M
authors.lastname: Nauck
authors.affiliation: Institute for Community MedicineErnst Moritz Arndt University, University of Greifswald, Walther-Rathenau Straße 48, D-17475 Greifswald, GermanyInstitute of Clinical Chemistry and Laboratory MedicineUniversity of Greifswald, Greifswald, GermanyDZHK (German Center for Cardiovascular Research)Partner Site Greifswald, University of Greifswald, Greifswald, GermanyDepartamento de Ciências FarmacêuticasUniversidade Regional de Blumenau, Blumenau, Brazil.
authors.forename: Caio M M
authors.initials: CM
authors.lastname: Cordova
authors.affiliation: Institute for Community MedicineErnst Moritz Arndt University, University of Greifswald, Walther-Rathenau Straße 48, D-17475 Greifswald, GermanyInstitute of Clinical Chemistry and Laboratory MedicineUniversity of Greifswald, Greifswald, GermanyDZHK (German Center for Cardiovascular Research)Partner Site Greifswald, University of Greifswald, Greifswald, GermanyDepartamento de Ciências FarmacêuticasUniversidade Regional de Blumenau, Blumenau, Brazil Institute for Community MedicineErnst Moritz Arndt University, University of Greifswald, Walther-Rathenau Straße 48, D-17475 Greifswald, GermanyInstitute of Clinical Chemistry and Laboratory MedicineUniversity of Greifswald, Greifswald, GermanyDZHK (German Center for Cardiovascular Research)Partner Site Greifswald, University of Greifswald, Greifswald, GermanyDepartamento de Ciências FarmacêuticasUniversidade Regional de Blumenau, Blumenau, Brazil.
authors.forename: Henry
authors.initials: H
authors.lastname: Völzke
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005858:Germany; D006801:Humans; D007455:Iodine / Q000097:blood* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D013972:Thyrotropin / Q000097:blood*; D055815:Young Adult
chemical_list: D013972:Thyrotropin; D007455:Iodine