The hypothalamus and pituitary gland are also involved in sodium regulation by making and releasing vasopressin, known as anti-diuretic hormone, into the bloodstream. Like aldosterone, vasopressin acts in the kidney, but it causes it to reduce the amount of water released into urine. With more vasopressin production, the body conserves water, resulting in a lower concentration of plasma sodium. Certain types of cancer cells produce vasopressin, leading to hyponatremia. Symptoms of moderate hyponatremia include tiredness, disorientation, headache , muscle cramps, and nausea.
Severe hyponatremia can lead to seizures and coma.
These neurological symptoms are thought to result from the movement of water into brain cells, causing them to swell and disrupt their functioning. In most cases of hyponatremia, doctors are primarily concerned with discovering the underlying disease causing the decline in plasma sodium levels. Death that occurs during hyponatremia is usually due to other features of the disease rather than to the hyponatremia itself. Diagnosis Hyponatremia is diagnosed by acquiring a blood sample, preparing plasma, and using a sodium-sensitive electrode for measuring the concentration of sodium ions. Unless the cause is obvious, a variety of tests are subsequently run to determine if sodium was lost from the urine, diarrhea, or from vomiting.