title: Subclinical hypothyroidism: a 'laboratory-induced' condition?
abstract: OBJECTIVE
  In current literature and guidelines, there is a tendency to define absolute TSH concentrations at which patient follow-up or even pharmaceutical intervention should be initiated. As TSH concentrations depend on the analytical method/platform used for TSH quantification, absolute cut-off values may pose threats for uniform clinical decision-making. In this study we therefore set out to clarify to what extent the method/platform and the reference values applied for TSH influence the clinical interpretation of thyroid parameters.
  
  
  METHODS
  We retrospectively analyzed anonymous TSH results from the Dutch external quality assessment program (EQAS) in relation to reference values advised by different manufacturers. We also examined TSH/free thyroxin (fT4) reference ranges and prevalence of thyroid pathology among different Dutch laboratories, including four cases in which a switch in the measuring platform was made.
  
  
  RESULTS
  Our data show that interpretation of thyroid parameters is not only influenced by between-method/platform variation, but is also substantially affected by the variation in TSH/fT4 reference intervals applied in individual laboratories. Additionally, we show that the transition to a novel analytical method/platform can result in a shift in the prevalence of thyroid pathology, especially for subclinical hypothyroidism.
  
  
  CONCLUSIONS
  Subclinical hypothyroidism can be a 'laboratory-induced' condition. This is an undesirable situation in regard to the clinical implications such a diagnosis can have for patients.
authors.affiliation: Clinical LaboratoryCatharina Hospital, Michelangelolaan 2, 5623 EJ Eindhoven, The NetherlandsClinical LaboratoryMeander Medical Center, Maatweg 3, 3813 TZ Amersfoort, The NetherlandsClinical LaboratoryMáxima Medical Center, De Run 4600, 5504 DB Veldhoven, The NetherlandsClinical LaboratorySint Anna Hospital, Bogardeind 2, 5664 EH Geldrop, The NetherlandsClinical LaboratoryUniversity Medical Center Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands Karlien.Coene@catharinaziekenhuis.nl.
authors.forename: Karlien L M
authors.initials: KL
authors.lastname: Coene
authors.affiliation: Clinical LaboratoryCatharina Hospital, Michelangelolaan 2, 5623 EJ Eindhoven, The NetherlandsClinical LaboratoryMeander Medical Center, Maatweg 3, 3813 TZ Amersfoort, The NetherlandsClinical LaboratoryMáxima Medical Center, De Run 4600, 5504 DB Veldhoven, The NetherlandsClinical LaboratorySint Anna Hospital, Bogardeind 2, 5664 EH Geldrop, The NetherlandsClinical LaboratoryUniversity Medical Center Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands.
authors.forename: Ayse Y
authors.initials: AY
authors.lastname: Demir
authors.affiliation: Clinical LaboratoryCatharina Hospital, Michelangelolaan 2, 5623 EJ Eindhoven, The NetherlandsClinical LaboratoryMeander Medical Center, Maatweg 3, 3813 TZ Amersfoort, The NetherlandsClinical LaboratoryMáxima Medical Center, De Run 4600, 5504 DB Veldhoven, The NetherlandsClinical LaboratorySint Anna Hospital, Bogardeind 2, 5664 EH Geldrop, The NetherlandsClinical LaboratoryUniversity Medical Center Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands.
authors.forename: Maarten A C
authors.initials: MA
authors.lastname: Broeren
authors.affiliation: Clinical LaboratoryCatharina Hospital, Michelangelolaan 2, 5623 EJ Eindhoven, The NetherlandsClinical LaboratoryMeander Medical Center, Maatweg 3, 3813 TZ Amersfoort, The NetherlandsClinical LaboratoryMáxima Medical Center, De Run 4600, 5504 DB Veldhoven, The NetherlandsClinical LaboratorySint Anna Hospital, Bogardeind 2, 5664 EH Geldrop, The NetherlandsClinical LaboratoryUniversity Medical Center Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands.
authors.forename: Pauline
authors.initials: P
authors.lastname: Verschuure
authors.affiliation: Clinical LaboratoryCatharina Hospital, Michelangelolaan 2, 5623 EJ Eindhoven, The NetherlandsClinical LaboratoryMeander Medical Center, Maatweg 3, 3813 TZ Amersfoort, The NetherlandsClinical LaboratoryMáxima Medical Center, De Run 4600, 5504 DB Veldhoven, The NetherlandsClinical LaboratorySint Anna Hospital, Bogardeind 2, 5664 EH Geldrop, The NetherlandsClinical LaboratoryUniversity Medical Center Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands.
authors.forename: Eef G W M
authors.initials: EG
authors.lastname: Lentjes
authors.affiliation: Clinical LaboratoryCatharina Hospital, Michelangelolaan 2, 5623 EJ Eindhoven, The NetherlandsClinical LaboratoryMeander Medical Center, Maatweg 3, 3813 TZ Amersfoort, The NetherlandsClinical LaboratoryMáxima Medical Center, De Run 4600, 5504 DB Veldhoven, The NetherlandsClinical LaboratorySint Anna Hospital, Bogardeind 2, 5664 EH Geldrop, The NetherlandsClinical LaboratoryUniversity Medical Center Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands.
authors.forename: Arjen-Kars
authors.initials: AK
authors.lastname: Boer
mesh_terms: D058070:Asymptomatic Diseases; D003657:Decision Making; D020249:Hormone Replacement Therapy / Q000379:methods*; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000175:diagnosis* / Q000188:drug therapy; D009426:Netherlands; D011785:Quality Assurance, Health Care; D012016:Reference Values; D012189:Retrospective Studies; D013960:Thyroid Function Tests / Q000295:instrumentation / Q000379:methods*; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood* / Q000627:therapeutic use
chemical_list: D013972:Thyrotropin; D013974:Thyroxine