Thyroid dysfunction and the state of the GH/IGF-1 system in adolescents with type 1 diabetes mellitus

Purpose: to determine the relationship between the functional state of the pituitary-thyroid system and the growth hormone/insulin-like growth factor type 1 (GH/IGF-1) system in adolescents with type 1 diabetes mellitus (DM1) during puberty Material & Methods: 165 children (85 girls (51,5%) and 80 boys (48,5%) aged 8 to 18 years old who have DM1 and are in the endocrinology department of the State Institution "Institute for Children and Adolescents Health Care at the National Academy of Medical Sciences of Ukraine" (SI "ICAHC NAMS"). The criterion for inclusion in the study was the duration of DM1 for more than one year (from 1 to 16 years). The level of thyrotropin (TSH), free fractions of thyroxin (fT4) and triiodothyronine (fT3), GH and IGF-1 was determined and the ratio (fT3/fT4 and TSH/fT4) was calculated. Study participants were divided into groups depending on the level of sexual development (T1-T4) at the time of the study, assessed by the Marshall & Tanner scale (Marshall & Tanner, 1969; Marshall & Tanner, 1970); functional state of the pituitary-thyroid system: (euthyroidism (TSH/fТ4 <0,19 c.u.), minimal thyroid insufficiency (0,19 c.u. ≤ TSH/fТ4 ≤0,29 c.u.), with subclinical hypothyroidism (TSH/fТ4 >0,29 c.u.) (Turchina et al., 2016). Results: it was found that among adolescents with DM1, almost every child has signs of thyroid dysfunction. An increase in the fT3 level and the fT3/fT4 ratio were more often diagnosed. The frequency of increase in the level of TSH and the ratio of TSH/fT4 fluctuated widely and depended on the sexual development of the child. More often, signs of SGH were determined during early puberty (23,5%), which probably exceeded those in prepubertal (16%, Pφ<0,05), proper (8,9%, Pφ<0,05) and late puberty (6,1%, Pφ<0,05). These changes indicate the tension of the thyroid system at the beginning of puberty, which is the basis not only for an increase in the risk of thyroid pathology in this period of puberty, but also for violations of physical and sexual development. Conclusions: almost a third of adolescents with DM1 had signs of thyroid insufficiency of varying degrees, which was most often determined during early puberty. The progression of thyroid insufficiency was accompanied by a decrease in the level of GH and IGF-1.