Introduction:
Autoimmune thyroid disorders are frequent. Patients diagnosed with these autoimmune thyroid diseases (AITD) are at high risk of developing other autoimmune diseases (AD), which at times, can be fatal.

Aim:
The aim of this study is to identify epidemiological, clinical, and biological characteristics of the different associations of organ-specific AD and non-organ-specific AD or systemic diseases with AITD and compare our findings with that found in literature.

Patients and methods:
It is a descriptive retrospective single institution study. We collected data from 113 patients diagnosed with a thyroid disorder associated with an autoimmune disease-either organ-specific autoimmune disease or systemic disease- hospitalized over a period of 18 years.

Results:
The sex ratio (F/M) was 3.52. The median age of occurrence of the AITD was 38.22 years’ old. The aetiology of the AITD was mainly Hashimoto’s disease in 69 patients followed by Grave’s disease in 19 patients. Seventeen types of AD were identified in association with the AITD. The most frequent organ-specific AD associated with the thyroid disorder was type 1 diabetes mellitus (41 patients), vitiligo (16 patients) and pernicious anaemia (16 patients). Systemic lupus erythematous (12 cases) and Sjogren’s disease (12 cases) were the most common systemic diseases associated with the AITD.

Conclusion:
AITD are frequent and can be associated with one or more autoimmune diseases. These AD can sometimes be revealing or on the contrary can emerge years later after the diagnosis of the dysthyroidism. A long-term follow-up is warranted in all patients diagnosed with an autoimmune disease.