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Editor,—An increased prevalence of autoimmune hypothyroidism is well documented in Turner’s syndrome. Although the risk is greatest in adulthood, it does extend in to childhood and adolescent years.1 It has been our policy to check venous thyroid stimulating hormone (TSH) and thyroxine on an annual basis in our Turner clinic. However, struck by the low incidence of positive results, and conscious that the clinic visit is often spoiled for the child because of apprehension over impending venepuncture, we decided to review our approach.
The case notes of all girls attending the Turner clinic since its inception in 1989 were examined. Data were available on 74 girls whose mean age at most recent thyroid function testing was 12.9 years (range, 1.1 to 25.3). Normal thyroid function test results were obtained in 66 of the girls in a total of 202 tests. Five of the girls had transient small increases in TSH (6–11.8 mU/I) with normal thyroxine, and subsequent return of TSH to normal (< 5 mU/1). Only three of the girls, aged 9.7, 11.9, and 25.3 years, were hypothyroid and this was decompensated in only one patient, the youngest child. All three cases were positive for microsomal antibody and two of the girls also had detectable thyroglobulin antibody titres. The diagnosis of thyroid abnormality was suspected clinically in two of the cases, because of tiredness and poor growth in the girl with decompensated hypothyroidism and obesity and a goitre in the other.
In the light of these results we feel that annual venous thyroid function testing in all girls with Turner’s syndrome is probably unjustified. Instead, we propose to measure venous thyroxine, TSH, and thyroid autoantibodies when pituitary function testing is being carried out before growth hormone treatment and when gonadal function is assessed at age 10–11 years. We plan to assess the girls clinically at each review and if hypothyroidism is suspected, we will initially test TSH using capillary filter strips as this method is generally much better tolerated than venous sampling.