Severe Symptomatic Anemia as a Rare Initial Manifestation of Type 3 Polyglandular Autoimmune Syndrome: A Case Report.

Autoimmune polyglandular syndrome type 3 (APS-3) is an uncommon condition marked by autoimmune thyroid disease (ATD) linked with other autoimmune issues, excluding Addison's disease. We report a case of a 41-year-old man who was hospitalized due to exhaustion and macrocytic anemia, later diagnosed with APS-3, which included Hashimoto's thyroiditis, pernicious anemia resulting from autoimmune gastritis, and pre-existing vitiligo. Diagnostic results indicated positive intrinsic factor antibodies, a gastric biopsy compatible with gastritis, elevated thyroid peroxidase antibodies, and significant findings from a thyroid ultrasound. Treatment included parenteral vitamin B12, which improved anemia, while for mild hypothyroidism, a watchful waiting approach was taken. This case report highlights the importance of conducting a systematic evaluation of anemia in the diagnosis and management of APS-3. Although anemia is not typically recognized as a characteristic feature of APSs, it can present as pernicious anemia secondary to autoimmune gastritis. These anemias can be significant and severely limiting, often causing pronounced symptoms that greatly impact patients' daily lives, further emphasizing the need for timely diagnosis and appropriate management.