Originally posted 2014-07-05 13:41:23. Republished by Blog Post Promoter Hypokalemia is a serum potassium level less than 3.5 mEq/L or 3.5 mmol/L.  This indicates depletion in the normal potassium levels in the body, a potential life-threatening emergency and can be fatal. Causes Gastrointestinal losses Vomiting Diarrhea Prolonged nasogastric suctioning Nutrition and metabolism Low potassium diet...