Vnitr Lek 2006, 52(10):900-905

Is decreased thyroid echogenity a good indicator of thyroid autoimmune disorder?

M. Dvořáková^*, M. Hill, J. Čeřovská, Z. Novák, I. Šterzl

Endokrinologický ústav, Praha, ředitel doc. MUDr. Vojtěch Hainer, CSc.

Introduction:
Thyroid gland with mildly decreased or significantly decreased echogenity is indicating possible autoimmune disorder even before first symptoms, i.e. change in laboratory tests measuring the level of thyroid hormones and antibodies to thyroid antigens occur. Target: to consider changes in thyroid gland echogenity suspecting thyroid autoimmune disorder and to determine antibodies to thyroid antigens in the respective type of thyroid echogenity (increased, normal, mildly decreased or significantly decreased) to consider the activity of autoimmune thyropathies related to echogenity and to compare these factors.

Methods:
Echogenity of the thyroid gland was examinated in randomly selected population (n = 1 055, 360 male, 695 female) in 11 regions of the Czech republic, all presented with urinary iodine concentration > 100 μg/L of urine. The echogenity was determined in 4-level scale as increased (1), normal (0), mildly decreased (-1) and significantly decreased (-2). Texture of thyroid was evaluated in 2-level scale as homogenous or non-homogenous. For the evaluation of the relation between echogenity type (1 to -2) and TgAb, and between the type of echogenity and TOPAb frequence analysis (logarithm-linear modules) was used, i.e. the complete module was compared with the measured values.

Results:
the selected adults (695 female, 360 male) with urinary iodine concentration > 100 μg/L of urine presented with increased echogenity in 2 females (0,28 %) and 1 male (0,28 %), normal echogenity in 281 females (40,42 %) and 206 males (57,22 %), mildly decreased echogenity in 288 females (41,43 %) and 128 males (35,56 %) and significantly decreased echogenity in 124 females (17,84 %) and 25 males (6,95 %). The biggest group, both in males and in females, presented with normal and mildly decreased echogenity. Homogenous thyroid gland structure was found in 223 females (32,08 %) and 220 males (61,11 %). Non-homogenous texture was found in 472 females (67,92 %) and 140 males (38,89 %). Frequence analysis both in males and in females was focused on: 1. relation between the echogenity (ECHO) and TgAb: in females with positive TgAb (14,23 %), significant relation to ECHO can be seen (p < 0,0001), in contradiction to males; 2. relation between the echogenity (ECHO) and TPOAb: this relation is very significant both in males and in females (p < 0,0001); 3. mutual relation between TgAb and TPOAb: both in males and in females very significant (p < 0,0001); positive relation between antibodies can be seen. Positive presence of antibodies can be found less frequent, negative presence of both antibodies is more frequent; 4. relation between the echogenity, TgAb and TPOAb: no statistic significance was found.

Conclusion:
Homogenous thyroid gland structure was mainly found in males and, on the contrary, non-homogenous structure in females. In 52,7 % of adults with significantly decreased echogenity, autoimmune disorder was confirmed in laboratory tests at the same time. With echogenity increasing, TgAb and TPOAb decreased, vice versa. Sonography, evaluating decreased echogenity, can be an early indicator of serious thyropathies before function parameters and clinical symptoms appear. Detected risky adults with sonographic signs of autoimmune disorder have to be monitored and respective treatment considered and started at the very first occurence of positive antibodies even if the function is still normal.

Keywords: sonography; decreased echogenity; significantly decreased echogenity; autoimmune disorder; antibodies to thyroid peridoxidasis; antibodies to thyroglobuline

Received: June 26, 2006; Published: October 1, 2006  Show citation