Endocrine Abstracts

Introduction: Children with Down syndrome (trisomy-21/T21) are at risk of developing congenital and early (diagnosed ≤1 year) hypothyroidism. Our current monitoring follows the Down Syndrome Medical Interest Group (DSMIG) guidance: performing thyroid function tests (TFT) at birth and 12 months.

Aims/objectives: 1) Determine the incidence of congenital/early hypothyroidism in babies with T21 and determine long-term thyroid function outcomes (by age 4-years).

2) Audit local practice against DSMIG guidelines.

Methods: We identified children with T21 born in our region over 10years: June 2007-June 2017. We reviewed their new-born screening (NBS), laboratory TFT, radiological results and follow-up input.

Outcome: Eighty-five children fulfilled the criteria (M:F sex ratio:1.58, incidence 0.95/1,000 livebirths). Day 5–7 NBS results were available for 84 patients (99%). Four children (4.8%, M:F 1:1) were diagnosed with congenital hypothyroidism requiring thyroxine treatment. Of these, 2 had normal NBS results (2.4%). 30/84 (36%) babies had transiently abnormal TFTs within 1 year. The majority occurred within month one of life (n=25, 83%), and were mostly elevated TSH values (n=13, 43%). 93% (n=28) had normal TFTs by 15months and of the remaining 2, one had normal TFTs by age 3-years and one has untreated persistent compensated hypothyroidism at age 2. Compliance with DSMIG guidelines:

• At birth: Between June 2007–2012, 40.5% (15/37 patients) had venous TFTs checked, compared to 81% (38/47) over July 2012–2017.

• 12-months: Between June 2007–2012, 76% (28/37) had venous TFTs; compared to 96% (45/47) over July 2012–2017.

Discussion: Our regional sex and birth rates for T21 compare with national rates (SR 1.3; BR 1.08 in 1000). Our incidence of congenital/early hypothyroidism in children with T21 (4.8%) compares with reported rates (1–20%). The majority of abnormal TFTs are transient and don’t require treatment. Over the second half of the 10-year period, compliance with DSMIG guidelines improved significantly.