Nephrology, what causes low sodium?

Hyponatremia: Hyponatremia (h) is caused by many causes. Some are diuretic use, cirrhosis of the liver and syndrome of inappropriate ADH (vasopressin) secretion, among other. To see a more detailed listing of the causes of h, go to this link: http://www.Mayoclinic.Com/health/hyponatremia/ds00974/dsection=causes.

Many causes: Hormone problems, sometimes related to infections, cancer, lung, heart or liver problems can cause the kidneys to retain extra water and dilute the sodium in the blood. Sometimes medications, or extreme drinking of water can lower sodium, too. Keep in mind that high sugar, cholesterol and protein levels can make the sodium seem low when it is really normal.

Low sodium: Several conditions and medications can cause low sodium. You need further test and urine test.

Water disorder : I am assuming you mean low measured sodium level in your blood. That is a issue of sodium relative to water in your blood. A low blood sodium is an water problem and suggest excessive water relative to measured sodium. A kidney doctor should be able to work this condition up. Has many causes and is often a complex dosprder. Many assumptions in my answer.