title: Final diagnosis in children with subclinical hypothyroidism and mutation analysis of the thyroid peroxidase gene (TPO).
abstract: OBJECTIVE
  To determine the final diagnosis of patients with subclinical hypothyroidism (SCH), and to perform mutation screening of the thyroid peroxidase gene (TPO).
  
  
  METHODS
  Infants with SCH without an identified etiology were included in the study. Patients with thyroid dysgenesis were excluded. Children > or = 2 years of age, and still on L-thyroxine (LT4) treatment underwent a diagnostic algorithm. After LT4 was discontinued for 4 weeks, thyroid function tests (TFT) were obtained. A perchlorate discharge test (PDT) was performed in patients with normal thyroid ultrasound but abnormal TFT. Sequence analysis of TPO was studied in all children who underwent a PDT.
  
  
  RESULTS
  Forty-eight patients (23 males and 25 females) completed the trial. Among these children, 19 (39.5%) had transient SCH, and 29 (60.5%) had permanent SCH. Among patients with permanent SCH, 19 had thyroid hypoplasia, six had partial iodide organification defect with positive PDT, and four had other dyshormonogenesis with negative PDT. Mean LT4 dose before the medication ceased was 1.2 +/- 0.5 microg/kg/day in transient cases, and 1.7 +/- 0.4 in those with permanent SCH (p < 0.05). No TPO mutation was detected. However, in five patients, seven different previously known TPO polymorphisms were detected: c.102C > G, L4L; > A, A576A; c.2088C > T, D666D; c.2263A > C, T725P; c.2630 T >C, V847A.
  
  
  CONCLUSIONS
  LT4 treatment should be stopped after the age of 2 years in infants with SCH without a definite pathology of the thyroid gland to exclude cases with transient hypothyroidism. Additionally, we should consider particularly thyroid gland hypoplasia, and also partial defects in iodide organification in infants with SCH.
authors: Department of Pediatrics, Division of Endocrinology, Akdeniz University Hospital, Antalya, Turkey. drdoga@hotmail.com
authors: Doga
authors: D
authors: Turkkahraman
authors: Ozgul M
authors: OM
authors: Alper
authors: Funda
authors: F
authors: Aydin
authors: Akin
authors: A
authors: Yildiz
authors: Suray
authors: S
authors: Pehlivanoglu
authors: Guven
authors: G
authors: Luleci
authors: Sema
authors: S
authors: Akcurin
authors: Iffet
authors: I
authors: Bircan
mesh_terms: D000465:Algorithms; D001324:Autoantigens / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D004252:DNA Mutational Analysis; D003937:Diagnosis, Differential; D005260:Female; D020249:Hormone Replacement Therapy; D006801:Humans; D007037:Hypothyroidism / Q000175:diagnosis* / Q000188:drug therapy / Q000209:etiology / Q000235:genetics*; D007223:Infant; D007231:Infant, Newborn; D007453:Iodide Peroxidase / Q000235:genetics*; D033862:Iron-Binding Proteins / Q000235:genetics*; D008297:Male; D050033:Thyroid Dysgenesis / Q000150:complications / Q000175:diagnosis / Q000235:genetics; D013960:Thyroid Function Tests; D013974:Thyroxine / Q000008:administration & dosage
chemical_list: D001324:Autoantigens; D033862:Iron-Binding Proteins; C056658:TPO protein, human; D007453:Iodide Peroxidase; D013974:Thyroxine