title: Thyroid hormone and its metabolites in relation to quality of life in patients treated for differentiated thyroid cancer.
abstract: BACKGROUND
  Levothyroxine (LT4) is the standard of care in patients with hypothyroidism. Despite this replacement therapy, quality of life (QoL) remains impaired in a substantial amount of patients. The reasons for this are still a matter of debate. Suggested causes include lack of endogenous T3 secretion by the thyroid, changes in other thyroid hormone metabolites and interference by autoimmune processes.
  
  
  OBJECTIVE
  To investigate the association between thyroid function tests (TFTs) and QoL in patients with a history of differentiated thyroid cancer on LT4 monotherapy. These patients lack endogenous thyroidal T3 secretion in the absence of autoimmune disease.
  
  
  METHODS
  This is a cross-sectional study in 143 patients (69·2% female). Initial therapy consisted of total thyroidectomy followed by radioiodine ablation minimally one year before inclusion. We assessed health-related QoL (RAND-36), thyroid-specific QoL (ThyPRO) and fatigue with the Multidimensional Fatigue Inventory. Extensive TFTs were assessed, including 3,5-diiodo-L-thyronine (3,5-T2).
  
  
  RESULTS
  Mean age was 50·2 years and mean time since diagnosis was 8·4 years. Median TSH was 0·042 mU/l, total T4 145·0 nmol/l, free T4 25·6 pmol/l, total T3 1·93 nmol/l, reverse T3 0·53 nmol/l and 3,5-T2 0·86 nmol/l. Multiple linear regression analyses did not show any association between QoL and the different TFTs, including T4/T3 and 3,5-T2/T3 ratios reflecting peripheral metabolism.
  
  
  CONCLUSIONS
  We did not find any association between TFTs and QoL in athyreotic patients on LT4 monotherapy. Our data do not provide evidence that a slight increase in dose improves fatigue or well-being in hypothyroid patients on LT4 therapy.
authors.affiliation: Division of Endocrinology, Department of Internal Medicine, Erasmus MC, Rotterdam, the Netherlands. e.massolt@erasmusmc.nl.|Rotterdam Thyroid Center, Department of Internal Medicine, Erasmus MC, Rotterdam, the Netherlands. e.massolt@erasmusmc.nl.
authors.forename: E T
authors.initials: ET
authors.lastname: Massolt
authors.affiliation: Division of Endocrinology, Department of Internal Medicine, Erasmus MC, Rotterdam, the Netherlands.|Rotterdam Thyroid Center, Department of Internal Medicine, Erasmus MC, Rotterdam, the Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: van der Windt
authors.affiliation: Division of Endocrinology, Department of Internal Medicine, Erasmus MC, Rotterdam, the Netherlands.|Rotterdam Thyroid Center, Department of Internal Medicine, Erasmus MC, Rotterdam, the Netherlands.
authors.forename: T I M
authors.initials: TI
authors.lastname: Korevaar
authors.affiliation: Department of Nuclear Medicine, Erasmus MC, Rotterdam, the Netherlands.
authors.forename: B L R
authors.initials: BL
authors.lastname: Kam
authors.affiliation: Division of Surgical Oncology, Department of Surgery, Erasmus MC Cancer Institute, Rotterdam, the Netherlands.
authors.forename: J W
authors.initials: JW
authors.lastname: Burger
authors.affiliation: Division of Surgical Oncology, Department of Surgery, Erasmus MC Cancer Institute, Rotterdam, the Netherlands.
authors.forename: G J H
authors.initials: GJ
authors.lastname: Franssen
authors.affiliation: Institute of Experimental Endocrinology, Charité-Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Lehmphul
authors.affiliation: Institute of Experimental Endocrinology, Charité-Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Köhrle
authors.affiliation: Division of Endocrinology, Department of Internal Medicine, Erasmus MC, Rotterdam, the Netherlands.|Rotterdam Thyroid Center, Department of Internal Medicine, Erasmus MC, Rotterdam, the Netherlands.
authors.forename: W E
authors.initials: WE
authors.lastname: Visser
authors.affiliation: Division of Endocrinology, Department of Internal Medicine, Erasmus MC, Rotterdam, the Netherlands.|Rotterdam Thyroid Center, Department of Internal Medicine, Erasmus MC, Rotterdam, the Netherlands.
authors.forename: R P
authors.initials: RP
authors.lastname: Peeters
mesh_terms: D005221:Fatigue; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011788:Quality of Life; D013960:Thyroid Function Tests; D013963:Thyroid Hormones / Q000097:blood* / Q000378:metabolism; D013964:Thyroid Neoplasms / Q000188:drug therapy*; D013974:Thyroxine / Q000627:therapeutic use*; D014284:Triiodothyronine / Q000097:blood
chemical_list: D013963:Thyroid Hormones; D014284:Triiodothyronine; D013974:Thyroxine