Hello, Welcome to Health Care Magic. I understand your concern. There are a lot of factors which could lead to low sodium levels in blood. I am not very familiar with your situation, since you didn t gave me a lot of information about your health status. Let me lists some factors which could be culprit in your case. - Hyponatremia (low sodium in blood) result when sodium is lost from the body or when both sodium and fluid are lost from the body, for example, during prolonged sweating, dehydration and severe vomiting or diarrhea. - Being on a low-sodium diet - Consuming excess water, for example during strenuous exercise, without adequate replacement of sodium, can also result in hyponatremia. - A number of medications can also lower blood sodium levels. Examples of these include diuretics, vasopressin, the sulfonylurea drugs, or other medications including anti-depressants and pain medications. - There are also other factors, but since you are saying that you were very healthy before, i would like just to mention them. Heart problems; Kidney diseases; Liver disease; Syndrome of inappropriate antidiuretic hormone secretion (SIADH), which makes your body retain water; adrenal gland disorders, such as Addison’s disease; hypothyroidism (under-active thyroid); primary polydipsia, a condition in which excess thirst makes you drink too much. Hope I answered to your question. Take Care, Dr. Ina Zaimi