title: Thyroid function tests in patients taking thyroid medication in Germany: Results from the population-based Study of Health in Pomerania (SHIP).
abstract: BACKGROUND
  Studies from iodine-sufficient areas have shown that a high proportion of patients taking medication for thyroid diseases have thyroid stimulating hormone (TSH) levels outside the reference range. Next to patient compliance, inadequate dosing adjustment resulting in under- and over-treatment of thyroid disease is a major cause of poor therapy outcomes. Using thyroid function tests, we aim to measure the proportions of subjects, who are under- or over-treated with thyroid medication in a previously iodine-deficient area.
  
  
  RESULTS
  Data from 266 subjects participating in the population-based Study of Health in Pomerania (SHIP) were analysed. All subjects were taking thyroid medication. Serum TSH levels were measured using immunochemiluminescent procedures. TSH levels of < 0.27 or > 2.15 mIU/L in subjects younger than 50 years and < 0.19 or > 2.09 mIU/L in subjects 50 years and older, were defined as decreased or elevated, according to the established reference range for the specific study area. Our analysis revealed that 56 of 190 (29.5%) subjects treated with thyroxine had TSH levels outside the reference range (10.0% elevated, 19.5% decreased). Of the 31 subjects taking antithyroid drugs, 12 (38.7%) had TSH levels outside the reference range (9.7% elevated, 29.0% decreased). These proportions were lower in the 45 subjects receiving iodine supplementation (2.2% elevated, 8.9% decreased). Among the 3,974 SHIP participants not taking thyroid medication, TSH levels outside the reference range (2.8% elevated, 5.9% decreased) were less frequent.
  
  
  CONCLUSIONS
  In concordance with previous studies in iodine-sufficient areas, our results indicate that a considerable number of patients taking thyroid medication are either under- or over-treated. Improved monitoring of these patients' TSH levels, compared to the local reference range, is recommended.
authors: Institute of Clinical Chemistry and Laboratory Medicine, Ernst-Moritz-Arndt University Greifswald, Ferdinand-Sauerbruch-Strasse, 17475 Greifswald, Germany. anke.hannemann@uni-greifswald.de.
authors: Anke
authors: A
authors: Hannemann
authors: Nele
authors: N
authors: Friedrich
authors: Robin
authors: R
authors: Haring
authors: Alexander
authors: A
authors: Krebs
authors: Henry
authors: H
authors: Völzke
authors: Dietrich
authors: D
authors: Alte
authors: Matthias
authors: M
authors: Nauck
authors: Thomas
authors: T
authors: Kohlmann
authors: Hans-Christof
authors: HC
authors: Schober
authors: Wolfgang
authors: W
authors: Hoffmann
authors: Henri
authors: H
authors: Wallaschofski