Autoimmune Thyroid Disorders in Autoimmune Addison Disease.

Area of Science:

• Endocrinology
• Autoimmune Diseases
• Thyroidology

Background:

• Autoimmune thyroid disease (AITD) is a frequent endocrine comorbidity in autoimmune Addison disease (AAD).
• Limited data exists on the prevalence and clinical progression of AITD in AAD patients.

Purpose of the Study:

• To comprehensively investigate the epidemiology and clinical characteristics of autoimmune thyroid disorders in patients with AAD.

Main Methods:

• Nationwide registry-based study.
• Inclusion of 442 patients with AAD and AITD from the Norwegian National Registry of Autoimmune Diseases.
• Analysis of diagnostic data, thyroid function tests, antibody status, treatment, and follow-up outcomes.

Main Results:

• 48% of 912 AAD patients had AITD; 42% had autoimmune hypothyroidism.
• Among those with available thyroid function tests, 20% had overt and 73% had subclinical hypothyroidism.
• Graves' disease (GD) affected 9% of patients; 21% of GD patients also had autoimmune hypothyroidism.
• At follow-up, 33% achieved normal thyroid hormone levels without treatment.

Conclusions:

• The actual prevalence of hypothyroidism in AAD may be lower than previously reported.
• Judicious consideration for initiating levothyroxine therapy is recommended.
• Long-term remission rates in AAD patients with Graves' disease are comparable to those without AAD.