Autoimmune Thyroid Disease (ATD) is associated with normal thyroid function (type 1) in most cases with variable incidence of functional evolution toward either hypo (type2, A or B if present or not goiter) or hyperthyroidism (type3).
To study the evolution of thyroid function in a longitudinal study, along a scale of six years, in relationship to thyroid volume, 128 subjects (80 females and 48 males), aged from 28 to 78 years, were considered, with the first diagnosis of ATD put in 2002 on the basis of high thyroid antibodies (TAb) and normal TSH (ATD type 1). They were rechecked after 6 years. TSH and TAb were tested by commercial chemiluminescent assay. Echography was performed with high resolution technology, applying a 7.5 MHz probe, both to calculate thyroid volume (multiplying the three diameters×π/6) and to evaluate echostructure considering three grades of hypoecogenicity.After 6 years TSH was stable in normal range in 71.5% of subjects (group 1,G1); sub clinical hypothyroidism (withTSH progression between 4.5 and 10 mUI/ml) was showed in 19% (G2);overt hypothyroidism (TSH>10) was demonstrated in 9.5% (G3). Only one subject has reached hyperthyroidism stage (TSH<0.01).
No relationship was demonstrated between TAb levels or thyroid echogenicity and TSH evolution, on the contrary for the thyroid volume.
|Initial volume (ml)||Volume after 6 years|
Our study seems to demonstrate no role of TAb or thyroid echogenicity in the functional evolution of TDA. Instead a significative reduction of thyroid volume should influence the evolution of the function of TDA to overt hypothyroidism. When the progression is limited to subclinical hypothyroidism no variations of thyroid size were found.
25 - 29 Apr 2009
European Society of Endocrinology