A low sodium level in the blood may result from excess water or fluid in the body, diluting the normal amount of sodium so that the concentration appears low..Information about hyponatre low sodium blood levels. Symptoms of hyponatreinclude headache, nausea, vomiting, lethargy, and confusion. Causes and diagnosis .Images. Psoriasis Medical Images. Red, A low sodium level in the blood may result from excess water or fluid in the body, bad breath. Treatment for .A sodium blood test may be used to detect low sodium or high sodium levels as part of a health checkup or to help evaluate conditions such as dehydration .