The swelling of the feet in the elderly can be caused by a variety of reasons, and is generally common for the following reasons: 1. heart failure, in addition to swelling of the feet, the patient also has panic, chest tightness, chest pain, wheezing, dyspnea, etc. 2. renal failure, in addition to swelling of the feet, the patient also has edema of the face and eyelids, which may be accompanied by proteinuria, hematuria, anemia, weakness, poor nausea, etc. 3. hypoproteinemia, in addition to swelling of the feet, the patient may also have multiple parts of the body with hypoproteinemia. 4. In addition to swelling of both lower extremities, patients may also have edema of multiple parts of the body with hypoproteinemia. 4. Hypothyroidism, in addition to swelling of both feet, patients may also have edema of multiple parts of the body, which is non-depressed, and thyroid function measurement can confirm the diagnosis of hypothyroidism. 5. Ultrasound can reveal arteriosclerosis or even deep vein thrombosis, and the edema can be localized with redness, swelling, heat and pain.