SAT-200 - Autoimmune Endocrinopathies Following Idiopathic Severe Aplastic Anemia in A Child

Aplastic Anemia is a rare condition, in which patients present with pancytopenia. Etiologies include exposure to radiation or medications, genetic disorders, and infectious causes; however, most cases are idiopathic. Among the latter, the majority are immune-mediated and have been associated with seronegative hepatitis, eosinophilic fasciitis, and thymoma (1). Rarely, it has been associated with systemic lupus erythematosus (2), while links to other autoimmune conditions are limited.

We present the case of a 5-year-old male with a prior diagnosis of idiopathic severe aplastic anemia that developed hyperthyroidism and type 1 diabetes, two years after disease onset. He had been diagnosed in 2023 with idiopathic aplastic anemia and was started on immunosuppressive therapy with antithymocyte globulin (ATG), cyclosporine, methylprednisolone, and eltrombopag, as well as prophylactic antibiotics. He was referred to endocrinology in August 2025 for abnormal thyroid function tests with a suppressed TSH and elevated total T3 and free T4. At this time, his bone marrow biopsy showed significant improvement in cellularity from 10% to over 60%. On examination, he was noted to be tachycardic, with elevated blood pressure and a goiter. Thyroid ultrasound demonstrated a diffusely enlarged, heterogeneous, and hypervascular gland. These findings were consistent with Graves’ disease versus possible Hashitoxicosis, for which the patient was started on atenolol and methimazole. Subsequent testing confirmed to have antibodies for both Graves' disease and Hashimoto's thyroiditis, with a predominance of hyperthyroid antibodies. In October 2025, his HgbA1c was 6.9% with the presence of three pancreatic islet cell antibodies. There had been elevated blood sugar readings documented since July; however, this was attributed to steroid therapy and later to hyperthyroid state. Aside from nocturia, the patient was asymptomatic. He was diagnosed with Type 1 diabetes mellitus and started on multiple daily injection insulin regimen.

This case illustrates an exceptionally rare occurrence of autoimmune endocrinopathies following idiopathic aplastic anemia in a pediatric patient. The occurrence of both Graves’ disease and type 1 Diabetes Mellitus following idiopathic aplastic anemia suggests an underlying shared immune dysregulation, raising consideration for a possible autoimmune polyglandular endocrine syndrome. These findings highlight the importance of screening for autoimmune endocrinopathies in patients diagnosed with idiopathic aplastic anemia.

1. Young NS. Aplastic anemia. New England Jornal of Medicine. 2018;379:1643–1656. doi:10.1056/NEJMra1413485
2. Chalayer É, Ffrench M, Cathébras P. Aplastic anemia as a feature of systemic lupus erythematosus: a case report and literature review. Rheumatology International. 2015;35(6):1073–1082. doi:10.1007/s00296-014-3162-4

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