title: Neonatal plasma TSH--estimated upper reference intervals for diagnosis and follow up of congenital hypothyroidism.
abstract: Age- and method-dependent plasma TSH reference intervals are essential for the diagnosis and management of congenital hypothyroidism. However, accurate reference intervals for plasma TSH have not been adequately defined due to the difficulties in obtaining samples from a healthy paediatric population. To overcome the difficulties in generating such intervals we estimated method-dependent plasma TSH upper-reference intervals by determining the blood spot TSH upper-reference interval from newborn blood spot TSH screening data (N = 10,697) and then derived method-dependent conversion factors for blood spot TSH to plasma TSH concentration from paired-blood spot and plasma TSH measurements. The upper reference interval for blood spot TSH of 3.04 mU/L was obtained from the 97.5th centile of the selected data. Using experimentally-derived conversion factors, estimates of plasma TSH upper reference intervals of 7.6, 6.3, 7.3, 8.3 and 6.5 mU/L were obtained for the Siemens Centaur, Abbott Architect, Roche Elecsys E170, Siemens Immulite 2000 and Beckman access HYPERsensitive TSH assays respectively. These estimated method-dependent plasma TSH upper reference intervals will be of great practical use to clinicians to diagnose and to follow up infants found to have increased blood spot TSH concentrations identified by Newborn Screening programmes.
authors.affiliation: Department of Medical Biochemistry and Immunology, University Hospital of Wales, Cardiff, UK. carol.evans@cardiffandvale.wales.nhs.uk
authors.forename: Carol
authors.initials: C
authors.lastname: Evans
authors.forename: Sarah
authors.initials: S
authors.lastname: Neale
authors.forename: John
authors.initials: J
authors.lastname: Geen
authors.forename: Gareth
authors.initials: G
authors.lastname: Jones
authors.forename: Leanne
authors.initials: L
authors.lastname: Mannings
authors.forename: Sandra
authors.initials: S
authors.lastname: Trow
authors.forename: Andrew
authors.initials: A
authors.lastname: Brain
authors.forename: Barry
authors.initials: B
authors.lastname: Nix
authors.forename: Richard
authors.initials: R
authors.lastname: Ellis
authors.forename: Sian
authors.initials: S
authors.lastname: Hancock
authors.forename: Brian
authors.initials: B
authors.lastname: Shine
authors.forename: Justin
authors.initials: J
authors.lastname: Warner
authors.forename: John W
authors.initials: JW
authors.lastname: Gregory
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Moat
mesh_terms: D003409:Congenital Hypothyroidism / Q000097:blood / Q000175:diagnosis*; D006801:Humans; D007231:Infant, Newborn; D016014:Linear Models; D015997:Neonatal Screening / Q000379:methods*; D012016:Reference Values; D013972:Thyrotropin / Q000097:blood*
chemical_list: D013972:Thyrotropin