Subclinical hypothyroidism in the first years of life in patients with Down syndrome

Background: subclinical hypothyroidism (sh), defined as mild thyroid-stimulating hormone (T sh) elevation with normal free thyroxine (FT4) levels and no symptoms, is common dur ing the first few years of life in Down syndrome (Ds) and can be self-limiting. Our objective was to confirm that sh is usually a transitory disorder and to identify the factors associated with spontaneous remission. Methods: We reviewed clinical histories of patients from the catalan Down syndrome Foundation ( cDsF) with Ds and sh diagnosed before 5 y of age. sh was defined as T sh 5.5–25 µU/ml (6 mo–4 y) or 4.13–25 µU/ml (4–7 y), with FT4 0.89–1.87 ng/dl (6 mo–4 y) or 0.96–1.86 ng/dl (4–7 y). results: Fifty-three patients with sh were identified, with an average age of 2.4 ± 1.1 y, median (range) Tsh at diagnosis 7.1 (4.2–23.9 µU/ml), and median (range) FT4 1.1 (0.9–1.7 ng/dl). sh resolved spontaneously in 39 cases (73.6%), with T sh at the most recent visit (mean age 6.7 ± 1.4 y) 3.9 (1.8–12.7 µU/ml). The rate of remission was significantly higher in patients without goiter (94.9 vs. 28.6%) and in those who were negative for antithyroid antibodies (89.7 vs. 42.9%). conclusion: sh in infants and preschool children with Ds is usually a transitory disorder, with remission in >70% of cases. The absence of goiter and thyroid autoantibodies was associated with a greater rate of spontaneous remission in our study.