THANK YOU for yours answers!!
I went to that site. My doctor would be happy to order it but there is a problem. I go to a clinic that is owned by a hospital, therefore it would be the hospital that bills me. I have no idea what the cost would be and we are stressed financially. Is there another reliable place to buy the test so that I don't have to go through the hospital?
I just had a bunch of blood tests and my sodium level is fine. I drink tons of water and eat salt.