Prospective Study of Post‐partum Thyroid Immune Dysfunctions in Type 1 Diabetic Women and in a Healthy Control Group Living in a Mild Iodine Deficient Area

Abstract

Second to diabetes mellitus, thyroid diseases are the most common endocrinopathies seen in pregnancy. The incidence of post‐partum thyroid dysfunction (PPTD) in women with type 1 diabetes mellitus is three‐fold increased. We determined the incidence of thyroid abnormalities in a well‐defined group of young subjects with type 1 diabetes and in an age‐matched healthy controls during and six months after pregnancy in an area of mild iodine deficiency. Twenty‐five out of twenty‐eight pregnant women completed the study. Fifteen were affected by type 1 diabetes and ten were controls. Our protocol of study consisted of four evaluations of each subject: in the first, in the second trimester, at delivery and six months after. At each control the patients were submitted to physical examination, thyroid ultrasonography, and determination of fT3, fT4, TSH, Antithyroglobulin antibodies (TgAbs), Antithyroperoxidase antibodies (TPOAbs). The variation of thyroid volume is statistically significant in both the diabetics and in the controls during the different times of observations. Four out of the fifteen diabetic pregnant patients (27%) developed a thyroid disease: two cases of post‐partum thyroiditis (PPT) and two cases of euthyroid benign nodular goiter, as confirmed by cytological examination. Two out ten controls (20%) developed positive antibodies (TPO Abs and TgAbs) since the first observation and showed an autoimmune thyroiditis six months after delivery. Both of them showed a familial history of thyroid disease. Our study suggests that in an area of mild iodine deficiency the incidence of thyroid autoimmunity in pregnant women is similar, whether diabetic or not; moreover, thyroid volume is increasing in the diabetics as much as in the non diabetics during pregnancy.