<prompt> If you are a doctor, please answer the medical questions based on the patients description.My sodium levels have gone down to 121 and I went into the hospital for 3 days and they gave me 3 bags of fluid to bring me up to 137 and released me and my regular doctor checked me and it is four weeks later and I am down to 131 now. He feels I may need to see a kidney specialist... any thoughts?? thanks  <response>: Hi, Thanks for writing in. A normal sodium level is between 135 and 145 milliequivalents per liter meL of sodium. Low sodium or Hyponatremia occurs when the sodium in your blood falls below 135 meL. Causes of low sodium awesome medications, such as some water pills diuretics, antidepressants and pain medications, Heart, kidney and liver problems. Syn Chat Doctor. Chronic, severe vomiting or diarrhea. 