The patient was an 85-year-old female who has been treated for hypertension and atrial fibrillation (Af). She has visited outpatient clinic and has received regularly general blood tests for every six months. Hemoglobin (Hb) level was stable as 11.2-12.3 g/dL and MCV 88fL from 2017, but it decreased suddenly to 5.2 g/dL and 64 fL in Sept 2020. She did not feel any symptoms or signs. Further evaluations revealed that occult blood in stool and upper and endoscopic exams were negative. About 40 days after starting sodium ferrous citrate, she developed edema anasarca, bilateral pleural effusion and heart failure. Laboratory test showed hypothyroidism, and then the administration of thyroid hormone and diuretics brought her early improvement. As to this impressive case report, general clinical progress and some discussion of the relationship among anemia, edema anasarca, heart failure and hypothyroidism would be described
