A Case of Autoimmune Polyendocrine Syndrome Type 3C with Warm-type Autoimmune Hemolytic Anemia which Developed during Treatment for Hashimoto's Thyroiditis.

The coexistence of warm-type autoimmune hemolytic anemia (wAIHA) and primary hyperparathyroidism (PHPT) in autoimmune polyendocrine syndrome type 3C (APS-3C) is rare. A 73-year-old female with Hashimoto thyroiditis was hospitalized with progressive anemia. The direct Coombs test results were positive. The cold agglutinin test results were negative, consistent with wAIHA. Imaging revealed splenomegaly on CT. Biochemical tests showed hypercalcemia and hypophosphatemia with markedly elevated levels of unmodified parathyroid hormone (PTH), suggesting PHPT. The anemia improved with the administration of prednisolone. Parathyroidectomy was performed, and the calcium and PTH levels were normalized. The coexistence of APS-3C, wAIHA, and PHPT has not been reported previously, thereby underscoring the novelty of this case.