Introduction: Graves’ disease is associated with various hematological abnormalities, including anemia, leucopenia, and thrombocytopenia. However, pancytopenia involving all three cell lines is a rare and often under-recognized manifestation of thyrotoxicosis. We present a case of newly diagnosed Graves’ disease complicated by pancytopenia, in which cell counts normalized rapidly following carbimazole initiation. Case: A 51-year-old female with underlying type 2 diabetes mellitus, hypertension, and dyslipidemia presented with dysphagia for 3 months, significant weight loss (from 95 to 75 kg over 6 months), and a 1-week history of fever, palpitations, tremors, orthopnea, and bilateral lower limb swelling. On examination, she was febrile (38.2°C) with bibasal crepitations, pitting edema up to the midshins, bilateral hand tremors, and a multinodular neck mass moving with deglutition. Investigations confirmed thyrotoxicosis (thyroid-stimulating hormone [TSH] 0.01 mIU/L, free T4 130.1 pmol/L, T3 >30.8 pmol/L) with positive autoantibodies (thyroid receptor antibody 31.9 IU/L, anti-thyroid peroxidase 195 IU/mL). Full blood count showed pancytopenia: white cell count 2.73 × 10⁹/L, hemoglobin 10.3 g/dL, and platelets 108 × 10⁹/L. Peripheral blood film suggested normocytic normochromic anemia with leucopenia and thrombocytopenia. Chest radiography showed cardiomegaly with fluid overload, and echocardiography revealed an ejection fraction of 77%. She was treated for impending thyroid storm secondary to pneumonia with Lugol’s iodine, hydrocortisone, propylthiouracil, and intravenous antibiotics. She was discharged on day 3 with a transition to carbimazole. At outpatient follow-up approximately 9 days later, thyroid function had improved significantly (free thyroxine 4 reduced from 130.1 to 29.34 pmol/L with suppressed TSH), and repeat full blood count demonstrated complete normalization of all three cell lines. Conclusion This case illustrates that pancytopenia can be a direct consequence of severe thyrotoxicosis and may reverse completely with effective antithyroid therapy. The temporal relationship between biochemical improvement and hematological recovery supports a causal link. Clinicians should be aware of this rare association to avoid misdiagnosis and unnecessary invasive investigations.
Pancytopenia ; Graves Disease ; Thyrotoxicosis