6718 Pancytopenia in a Patient with Graves’ Disease: An Interesting Case of a Thyrogastric Syndrome

Abstract Disclosure: A.E. De Rosairo: None. D. Patel, MD: None. D.H. Sacoto, MD: None. R. Belokovskaya: None. A.A. Franco-Akel, MD: None. Introduction: Polyglandular autoimmune syndromes (PAS) are rare polyendocrinopathies which are caused by an immune-mediated destruction of endocrine tissues, characterized by the failure of several endocrine glands and nonendocrine organs. PAS Type 3 is defined as the combination of thyroid autoimmune disease (TAD) and other autoimmune disorders (other than Addison disease), and is divided into 4 subtypes. PAS type 3B (thyrogastric syndrome) is combination of TAD and pernicious anemia. This case highlights an interesting presentation of an individual with Graves’ disease (GD) who developed pancytopenia with symptomatic anemia secondary to severe vitamin B12 deficiency due to pernicious anemia. Case: A 44-year-old Hispanic male with medical history of GD (diagnosed 3 years ago controlled with methimazole 20mg daily) and hypertension presented to the ED with symptomatic anemia with worsening fatigue, dizziness, dyspnea, nausea, vomiting and non-bloody diarrhea for 3 weeks. Laboratory findings remarkable for pancytopenia, including leukopenia (white blood cell 2.44 K/uL), thrombocytopenia (platelets 138 K/uL), macrocytic anemia (hemoglobin 4.9g/dL, hematocrit 14.4%, MCV 117.1fl), LDH 3231 U/L, reticulocytes count 3.231%. Other lab values were within normal limits. Peripheral blood smear noted teardrop cells, fragmented cells, polychromasia, poikilocytosis, and hypersegmented polymorphonuclear leukocytes. Patient received 4 units packed red blood cell with noted improvement in symptoms. Thyroid function tests were within normal limits hence methimazole was held to rule out methimazole induced pancytopenia. Bone marrow biopsy showed hypercelluar marrow with marked erythroid hyperplasia with left shift, no evidence of acute leukemia. Normal serum folate levels but vitamin B12 levels significantly low <150 pg/ml (232 - 1245 pg/mL) and intrinsic factor antibody positive (227.9AU/mL). Patient was started on vitamin B12 injections; thereafter, symptomatic anemia and pancytopenia resolved. Repeat TSH low (0.02 ulU/mL), free T4 1.9 ng/dL and thyroid stimulating Immunoglobulin 0.14 hence, patient was restarted on methimazole. Patient was clinically stable in subsequent follow up visits. Discussion: The patient with known TAD suddenly developed pancytopenia, with symptomatic megaloblastic anemia. Severe vitamin B12 deficiency and intrinsic factor antibody positive confirmed diagnosis of pernicious anemia which respond to cobalamin treatment and noticed resolution of pancytopenia. PAS type 3B was first described in the early 1960s and refers to the presence of thyroid autoantibodies in patients with pernicious anemia and it is inherited with a polygenic inheritance pattern. This case emphasizes that there can be coexistence of other autoimmune disorders and it is important to screen for other autoimmune disorders when suspected. Presentation: 6/3/2024