A case of simultaneous occurrence of Graves' disease and Hashimoto's thyroiditis

Introduction: Simultaneous occurrence of Hashimoto's thyroiditis (HT), and Graves' disease (GD) is rare.

Aims and objectives: We report a case of simultaneous occurrence of GD and HD, at presentation.

Case report: A 60-year-old lady presented with tremulousness of hands, palpitation, and excessive sweating. She had a history of weight loss and neck-swelling. Her weight was 46 kg, BMI 17, afebrile, regular pulse rate of 110/min with fine tremor in hands. Thyroid gland was symmetrically enlarged, firm, without any bruit, but mildly tender with lobular surface. There were no occular manifestations. Initial thyroid function tests (TFT) revealed: T3: 3.80 ng/ml (0.80-2.10), T4: 12.40 ug/dl (5.10-12), thyroid stimulating hormone (TSH): 0.20 μU/L (0.70-5). Her anti thyroperoxidase (TPO) antibody: 374 IU/ml (normal [nl.] <35) and TSH receptor antibody: 15 U/L (nl. <1) were both strongly positive. Ultrasonogram of thyroid revealed a hypoechoic enlarged gland. 99mTc pertechnetate scan showed an enlarged gland with increased uptake of radiocontrast: 17% (nl. 0.4-4%) with some patchy defects in both lower poles. Thyroid fine needle aspiration cytology (FNAC) showed sheets of Hurthle cells with abdunce of lymphocytes indicating HT. She was observed on beta blockers. Repeat TFT, 3 months later showed: T3: 4.20 ng/ml, T4: 14.40 ug/dl, TSH: 0.001 μU/L, with increased uptake on repeat scan.

Conclusion: HT rarely occurs following GD. Our case of an elderly lady with no eye signs, lobular, firm tender goiter with patchy uptake in both lower poles on Tc99m scan were odd points in diagnosing isolated GD. FNAC confirmed simultaneous HD with GD.