Efficacy of non invasive diagnostic procedures in evaluation of maternal autoimmune thyreoiditis effect on the fetus

Maternal autoimmune thyroid disease increases the incidence of foetal hypo and hyperthyreosis due to antithyroid antibodies and thyroid suppressive drugs passage through the placenta. Aim of the study: Primary aims: Correlation between antithyroid antibodies level in mothers and foetal serum with ultrasound estimation of foetal thyroid size and free thyroxin (fT4) in foetal blood; ultrasound morphology of foetal thyroid as diagnostic tool in estimation of foetal fT4 values. Secondary aims: to investigate correlation between foetal fT4 with ultrasonographic foetal biometry, therapeutical drug dosage used to treat maternal thyroid disease, and maternal thyroid status. Patients and methods: The study was conducted as a prospective follow up of 51 pregnants with autoimmune thyroid disease, 20 patients hyperthyroid, and 31 hypothyroid. Control group was consisted of 20 healthy pregnancies. Thyroid hormones and anti thyroid antibodies values were measured from blood sampled from mothers and from umbilical cord in foetuses, between 26-30 weeks of gestation. These included: fT4, TSH, antithyriod antibodies (anti thyreoperoxidase At-TPO, TSH receptor antibody-TRAK). At the same ultrasound estimation of foetal thyroid volume, foetal growth and morphology were assessed. The data were statistically analyzed using SPSS 15.0. Results: 40 % of foetuses in hyperthyreotic pregnancies were found with increased fT4 in cord blood. 48,4% foetuses from hypothireotic pregnancies were found to have increased fT4, and 3,2% were found to have decreased fT4 in cord blood. Maternal and foetal antithyroid antibodies were in obvious positive correlation. Maternal and foetal anti TPO correlated highly significant with standardized values of foetal fT4 (Spearman correlation coefficient: mother 0,396, p=0,004, foetus 0,466, p=0,001). Mean concentration of anti TPO in mother and foetus significantly differed in foetuses with normal and impaired foetal thyroid size (normal foetal thyroid size/increased foetal thyroid size/decreased foetal thyroid size: maternal anti TPO: 119 ± 247 vs 377 ± 506 vs 376± 422; Kruskal- Wallis: 10,726, p=0.005, foetal anti TPO: anti TPO 43,98 ± 63,99 vs 140,48 ± 136,99 vs 85,49 ± 88,42; ANOVA, F= 5,567, p 0,05 and foetal: 0,144, p> 0,05). fT4 and thyroid size were normal in 7 foetuses from mothers with negative anti TPO and TRAK antibodies. 70% of foetuses found with normal thyroid size had normal fT4 and impaired fT4 in 30%. In cases with increased thyroid valu