Sodium Urine test is done to measure the levels of Sodium in urine. It is a 24 hour test. Sodium is both a mineral and an electrolyte. It helps in maintaining fluid and electrolyte balance in body. The results of this test effected by the intake of water and salt. A 24 hour urine test means the measure of amount of urine produced in a complete day. It is generally prescribed by the physician after an abnormal report of blood sodium levels. This test can also be done on spot, in which the amount of sodium present in the urine is measured. This test can help doctors determine the reason for abnormal value of sodium also whether the kidneys are functioning properly.