The hyponatremia is caused by a relatively smaller loss in total body water. 1  any cause of hypovolemia such as prolonged vomiting, decreased oral intake, severe diarrhea. 2  diuretic use (due to the diuretic causing a volume depleted state and thence ADH release, and not a direct result of diuretic-induced urine sodium loss)
Biotin is safe but is not likely to do much to help your hair grow unless you are deficient in biotin, which is uncommon. A reasonable dose is 5 mg. However, you may get better results by taking a quality multivitamin, eating a healthy diet rich in organic fruits and vegetables, avoid junk food and getting adequate sleep.
The U.S. Food and Drug Administration (FDA) has not established a recommended dietary allowance (RDA) for biotin. According to the Food and Nutrition Board of the Institute of Medicine, 30 mcg is the daily adequate intake for adults 19 years of age and older, which can usually be achieved through dietary consumption.