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Published on: March 17, 2023
Permanent congenital hypothyroidism with blood spot thyroid stimulating hormone <10 mU/L
Jeremy H Jones1, Sarah Smith2, Catherine Dorrian2
1Department of Paediatric Endocrinology, Royal Hospital for Children, Glasgow, UK.
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.
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