الفهرس 
- Thyroid GlandOnly 14 pages are availabe for public view
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Abstract
Thyroid autoimmune disease is the most common of all autoimmune disorders. Some experts estimate that 75% of those affected are women. Approximately 90% of all hypothyroid, mostly due to Hashimoto’s autoimmune disease or chronic lymphocytic thyroiditis. It may start out silently, but the attack will eventually cause an inflammation and gradual destruction of thyroid gland and can go on for years with bad side effects. It can also cause nodules or lumps.
The thyroid gland may become firm, large, and lobulated in Hashimoto’s thyroiditis, but changes in the thyroid can also be nonpalpable. Enlargement of the thyroid is due to lymphocytic infiltration and fibrosis rather than tissue hypertrophy. Physiologically, antibodies against thyroid microsomes and/or thyroglobulin cause gradual destruction of follicles in the thyroid gland.
Owing to the relatively non-specific symptoms of initial hypothyroidism, HT is often misdiagnosed as depression, cyclothymia, chronic fatigue syndrome, fibromyalgia and, less frequently, as an anxiety disorder.
Summary
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So, detection of two autoantibodies is needed for diagnosis of HT; thyroid microsomal antibodies and/or thyroglobulin antibodies in the serum.
The aim of the present study is to compare between two approaches (automated Chemiluminescence and Indirect Immunoflourescence) in the terms of analytical sensitivity, specificity and cost effect for detection of thyroid autoantibodies.
Patients under study were subjected to full history taking, full clinical examination, and laboratory investigation including CBC, thyroid function tests and Thyroid autoantibodies [ thyroid antimicrosomal (AM-Ab) and antithyroglobulin (TgAb) antibodies] by automated chemiluminescence and indirect immunofluorescence.
In the present study, it was found that serum AM-Ab by CLIA showed significant positive correlation with serum TSH and significant negative correlation with age and hemoglobin. Additionally, there was no significant correlation between serum TgAb and TSH levels.
Moreover, the study revealed that there was high significant difference (P<0.01) between IIF and automated CLIA (at manufacturer’s cut-off 5.61 IU/ml) regarding positive and negative results of AM-Ab and that specificity of CLIA (at this
Summary
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cut off 5.61 IU/ml) was 72.9%, sensitivity was 68.2% , positive predictive value was 53.6% and negative predictive value was 83.3%. Also, the study showed that when adjusting a new cut-off value (at 369.02 IU/ml) of AM-Ab by CLIA according to Receiver-operating characteristic (ROC) curve analysis, there was no significant difference (P>0.05) between IIF and automated CLIA regarding results of AM-Ab that specificity of CLIA (at this new cut off 369.02 IU/ml) became 93.8%, sensitivity was 59.1%, positive predictive value was 81.3% and negative predictive value was 83.3%. In addition, the present study showed that all results regarding TgAb by IIF were negative while by CLIA, there were 37 (52.9%) positive and 33 (47.1%) negative results.
In conclusion, the present results suggested that regarding positive and negative results of AM-Ab by CLIA (at cut-off 5.61 IU/ml), CLIA showed low specificity and high sensitivity compared with IIF as a reference method. While results of AM-Ab by CLIA (at the new cut-off value 369.02 IU/ml), CLIA showed higher specificity and lower sensitivity. Also, all results regarding TgAb by IIF were negative while by CLIA showed positive and negative results of TgAb. In addition, regarding cost effect of measuring thyroid autoantibodies by the two approaches,
Summary
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it was found that using IIF is less in cost than using automated chemiluminescence.Differences in methodology used to assess AM-Ab and TgAb in AITD may contribute to the discrepancy between our study and other studies. Differences in race, age, nutritional habits and stage of the disease may also be contributable factors. So, we need to expand the patient number and do more further studies to assess these different methods.