Swelling of the feet in the elderly is often caused by hypoproteinemia, cardiac insufficiency, or water and sodium retention. Hypoproteinemia causes a decrease in the body’s colloid osmotic pressure, so that blood penetrates into the subcutaneous tissues, causing an increase in tissue fluid and leading to weight bearing in the feet. The specific cause is a decrease in the ability to synthesize protein due to liver insufficiency, so it causes hypoproteinemia in the body, or a decrease in protein intake in the body, which can also lead to hypoproteinemia. If the patient has cardiac insufficiency, this can lead to water and sodium retention or renal insufficiency. Since reduced urination can also lead to water and sodium retention in the body, swelling can also occur in the feet, which are most likely to be swollen because they are in the lowest position in the body.