Suddenly found swollen feet, if bilateral foot swelling persists for a few days or after a period of time, you may need to see a doctor in time. There are many causes of swollen feet: 1, kidney disease: if acute nephritis, chronic nephritis, nephrotic syndrome and other glomerular diseases, swelling of the feet or accompanied by eyelid, facial swelling; 2, heart system: if heart disease, causing cardiac insufficiency, to a certain extent can also cause swelling of the feet, also bilateral swelling of the feet; 3, liver disease: hepatitis to a certain extent, affecting the 3, liver disease: hepatitis to a certain extent, affecting the synthesis of albumin, causing hypoproteinemia, can also cause swelling of the feet, also bilateral swelling of the feet; 4, endocrine diseases: the most common is hypothyroidism, but hyperthyroidism can also cause swelling of the feet; 5, rheumatoid immune disease: can be detrimental to the kidneys and cause swelling of the feet.