title: Thyroid status in a large cohort of patients with mental retardation: the TOP-R (Thyroid Origin of Psychomotor Retardation) study.
abstract: OBJECTIVE
  Abnormalities in thyroid state may affect development and function of the brain and result in mental retardation (MR). Thyroid parameters have not been systematically investigated in institutionalized MR subjects. The objective is to measure thyroid parameters in a novel cohort of 946 institutionalized subjects.
  
  
  METHODS
  The TOP-R (Thyroid Origin of Psychomotor Retardation) study is a cross-sectional nation-wide multicentre study.
  
  
  METHODS
  Subjects with unexplained MR.
  
  
  RESULTS
  The majority of the MR subjects had thyroid parameters within the reference range used in our laboratory. Antiepileptic drugs (AEDs) use affected thyroid hormones (T4: 102·1 ± 1·2 vs 83·9 ± 1·2 nmol/l, P < 1 × 10(-24) ; FT4: 18·0 ± 0·2 vs 16·1 ± 0·2 pmol/l, P < 1 × 10(-9) ; T3: 1·72 ± 0·02 vs 1·57 ± 0·02 nmol/l, P < 1 × 10(-9) ; and rT3: 0·37 ± 0·01 vs 0·27 ± 0·01 nmol/l, P < 1 × 10(-28) in subjects without vs with AEDs). The prevalence of unrecognized primary hypothyroidism and hyperthyroidism was 5·2% and 2·8%, respectively.
  
  
  CONCLUSIONS
  We report thyroid parameters in a cohort of institutionalized subjects with MR. Our findings substantiate the fact that AEDs affect thyroid hormone levels. Future studies will be employed to investigate genetic causes of MR related to abnormalities in thyroid hormone homeostasis.
authors.affiliation: Department of Internal Medicine, Erasmus University Medical Centre, Rotterdam, The Netherlands.
authors.forename: Willem Edward
authors.initials: WE
authors.lastname: Visser
authors.forename: Yolanda B
authors.initials: YB
authors.lastname: de Rijke
authors.forename: Hans
authors.initials: H
authors.lastname: van Toor
authors.forename: Theo J
authors.initials: TJ
authors.lastname: Visser
mesh_terms: D000328:Adult; D000368:Aged; D000927:Anticonvulsants / Q000627:therapeutic use*; D002220:Carbamazepine / Q000627:therapeutic use; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D006980:Hyperthyroidism / Q000453:epidemiology; D007037:Hypothyroidism / Q000453:epidemiology; D008607:Intellectual Disability / Q000097:blood / Q000188:drug therapy* / Q000453:epidemiology; D000077213:Lamotrigine; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D010634:Phenobarbital / Q000627:therapeutic use; D010672:Phenytoin / Q000627:therapeutic use; D015995:Prevalence; D013961:Thyroid Gland / Q000187:drug effects* / Q000378:metabolism; D013972:Thyrotropin / Q000097:blood / Q000378:metabolism; D013974:Thyroxine / Q000097:blood / Q000378:metabolism; D014227:Triazines / Q000627:therapeutic use; D014284:Triiodothyronine / Q000097:blood / Q000378:metabolism; D014635:Valproic Acid / Q000627:therapeutic use
chemical_list: D000927:Anticonvulsants; D014227:Triazines; D014284:Triiodothyronine; D002220:Carbamazepine; D014635:Valproic Acid; D010672:Phenytoin; D013972:Thyrotropin; D013974:Thyroxine; D000077213:Lamotrigine; D010634:Phenobarbital