BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: Infants with permanent and occasionally severe CHT may have a screening TSH below the UK recommended lower cut-off. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.
BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS:Infants with permanent and occasionally severe CHT may have a screening TSH below the UK recommended lower cut-off. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.