Clinical and laboratory features of autoimmune thyroiditis in subjects of the cohort according to the results of screening

Abstract

Resume A retrospective analysis of the screening results was carried out (970 subjects of the cohort underwent an in-depth (4-fold) examination (at each visit: ultrasound examination of the thyroid gland, determination of the levels of thyroid-stimulating hormone (TSH) in the blood serum and antibodies to thyroid peroxidase (TPOAb), examination by an endocrinologist) for thyroid diseases. Medical examinations (visits) were carried out every 2 years.It was noted that within the cohort subjects, the most common clinical and laboratory variant of AIT was subclinical with preserved size and function of the thyroid gland or its transient decrease. The frequency of occurrence of the atrophic form of AIT is minimal (only 2/71 patients had a thyroid volume less than 6 ml) as well as the hypertrophic form (in 5/71 cases of AIT the thyroid volume exceeded 24 ml).Analysis of the combination of laboratory and instrumental criteria showed the dependence of the diagnosis of AIT on one of two examinations: Ultrasound (decreased echogenicity) or increased TPOAb. The proportion of each criterion was almost equal (echogenicity was decreased in 10 cases – 14,1%; TPOAb was increased in 16 cases – 22,5%). In most cases (43 cases – 60,6%) there was a combination of two criteria (decreased echogenicity and increased TPOAb). In one case (1,4%), against the background of an increased ratio of antibodies to thyroid peroxidase, an increased level of TSH was noted; ultrasonographic signs were normal. In the second case, against the background of decreased echogenicity of the thyroid gland and low TSH levels, ratio of antibodies to thyroid peroxidase is increased. In all cases, the patients did not report any clinical symptoms, i.e. it manifested as a subclinical form. The TSH level (in 70/71 cases) was within the normal range (0,3-4,0 mIU/l), but its level was significantly higher in patients with AIT (2,4±0,12 mIU/l) than in healthy individuals (TPOAb – normal and thyroid echogenicity – normal) 1,6±0,02 mIU/l; p<0,001.The simultaneous presence of high concentrations of TPOAb in the blood serum and sono -graphic criteria of AIT, including decreased echogenicity of the thyroid gland, increases after 2 years the risk of primary hypothyroidism (PHT) by 12,8 (5,19-31,61) times (p<0,001), in the case of TPOAb content in the blood serum – 29,9 IU/ml and higher, 9,4 (3,86-23,11) times – when the concentration of these autoantibodies TPOAb is more than 60 IU/ml.