title: Permanent congenital hypothyroidism with blood spot thyroid stimulating hormone <10 mU/L.
abstract: The UK recommended lower threshold for neonatal blood spot thyroid stimulating hormone (TSH) screening for congenital hypothyroidism (CHT) is 10.0 mU/L. Some laboratories use lower thresholds. This will lead to referral of mildly or unaffected infants but some will require thyroxine therapy.
  
  
  
  Laboratory referrals with a first or repeat capillary TSH between 8.0 and <10.0 mU/L were identified (January 2004 to March 2014). The outcome of these cases was examined.
  
  
  
  26 infants had one or more blood spot TSH values between 8.0 and 9.99 mU/L; 65% had transient elevated neonatal TSH while one is awaiting diagnostic challenge. The remaining eight (31%) have permanent CHT; three with dyshormonogenesis, two with thyroid ectopia and the others met the criteria for definite CHT. Two out of three with dyshormonogenesis presented with decompensated hypothyroidism.
  
  
  
  Infants with permanent and occasionally severe CHT may have a screening TSH below the UK recommended lower cut-off.
authors.affiliation: Department of Paediatric Endocrinology, Royal Hospital for Children, Glasgow, UK.
authors.forename: Jeremy H
authors.initials: JH
authors.lastname: Jones
authors.affiliation: Scottish Newborn Screening Laboratory, Southern General Hospital, Glasgow, UK.
authors.forename: Sarah
authors.initials: S
authors.lastname: Smith
authors.affiliation: Scottish Newborn Screening Laboratory, Southern General Hospital, Glasgow, UK.
authors.forename: Catherine
authors.initials: C
authors.lastname: Dorrian
authors.affiliation: Department of Paediatric Endocrinology, Royal Hospital for Children, Glasgow, UK.
authors.forename: Avril
authors.initials: A
authors.lastname: Mason
authors.affiliation: Department of Paediatric Endocrinology, Royal Hospital for Children, Glasgow, UK.
authors.forename: M Guftar
authors.initials: MG
authors.lastname: Shaikh
mesh_terms: D003409:Congenital Hypothyroidism / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D015997:Neonatal Screening / Q000379:methods*; D012016:Reference Values; D012017:Referral and Consultation; D013972:Thyrotropin / Q000097:blood*; D006113:United Kingdom
chemical_list: D013972:Thyrotropin
keywords: Congenital hypothyroidism; Newborn screening; Thyroid stimulating hormone; free thyroxine