This is a case of a 40-year-old female, who had been diagnosed with diffuse toxic goiter and has been maintained on antithyroid medications (propylthiouracil, which was eventually shifted to methimazole) for 11 years. She was admitted due to sudden onset slurring of speech and seizure episodes. She has a 4-month history of exertional dyspnea, difficulty initiating sleep, blurring of vision, pruritus, nausea, melena, abnormal uterine bleeding and appearance of skin lesions along her lower extremities. Upon assessment, there was noted with hypertension, azotemia and glomerular hematuria. Further diagnostics revealed positive c-ANCA (PR3-ANCA). Findings on imaging studies: 1) narrowing and dilatation of the segmental renal arteries indicative on nonspecific medium vessel vasculitis on abdominal CT angiography, 2) unremarkable cranial MRI with MRA. Given the occurrence within just a few months of signs and symptoms akin to small-vessel vasculitis in combination with positive c-ANCA, ANCA-associated vasculitis with rapidly progressive glomerulonephritis was considered. ANCA positivity after diagnosis of hyperthyroidism and treatment with antithyroid drugs has been reported in the literature. The patient did not consent for any invasive procedures (renal biopsy, colposcopy with biopsy, skin biopsy, endoscopy with biopsy). She was started on kidney replacement therapy and immunosuppression: induction therapy using glucocorticoids and IV cyclophosphamide therapy. After 3 months of therapy, there was resolution of extrarenal manifestations; however, there was no improvement in renal function and she remained on dialysis. Immunosuppressive therapy was eventually tapered off.