Quantification of antithyroperoxidase and antithyroglobulin antibodies, and thyrotrophin and free thyroxine in normal pregnant women

PURPOSE: to quantify the presence of antithyroperoxidase (anti-TPO) and antithyroglobulin (anti-TG) antibodies, and the plasmatic concentrations of thyrotropin (TSH) and free thyroxine (FT4) in normal pregnant women. METHODS: a hundred twenty-seven pregnant women, residing in São Paulo, aged from 14 to 44 years old and gestational age > 16 weeks, determined by ultrasound performed before the 20th week of pregnancy were included in a transversal study performed in the prenatal clinic of Santa Casa de Misericórdia de São Paulo, from January 2003 to September 2004. Pregnant women using medicines or with thyroidopathy history were excluded. Antithyroperoxidase and antithyroglobulin antibodies were quantified by chemiluminescence immunoassay. The immunofluorimetry technique by time-resolved was used for determining the thyrotrophin and free thyroxine. The Student's t test, with significance of 5%, was used for analyzing the results. RESULTS: the frequency of antithyroid antibodies was 12.6% (8.6% of anti-TPO antibodies, and 4.6% of anti-TG antibodies). The average of TSH concentrations was 2.13±1.0 µU/ml, and the average of T4L was 0.9±0.5 ng/dl. It was observed alteration of the thyroid function in ten pregnant women (8%). Three of them had diagnosis of hypothyroidism: one in the clinical form of the disease, with increased TSH and decreased FT4; two in the subclinical form with increased TSH and normal FT4. Five presented decreased TSH and increased FT4, consistent with clinical hyperthyroidism and two were diagnosed with subclinical hyperthyroidism, with decreased TSH concentrations only. CONCLUSIONS: the frequency of antithyroid antibodies was 12.6% in pregnant women, the antithyroperoxidase antibodies being predominant over the antithyroglobulin antibodies. It was observed some thyroid dysfunction in 8% of the cases with alterations of TSH and/or T4L.

Antibodies; Autoantibodies; Peroxidase; Thyroglobulin

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