Q. If a blood test shows that I have elevated sodium, does that mean I need to eat less salt? I’m already on a low-sodium diet to control my blood pressure.
A. No. Under normal circumstances, the body is very good at regulating blood sodium in a narrow range, regardless of how much salt you consume. Blood sodium that’s too high or too low can be a sign of many medical problems, which is why it’s measured as part of a standard blood panel. It’s not measured in order to determine whether you’re consuming too much salt.
Most sodium in the body is found in the blood. Along with other electrolytes (potassium and calcium), sodium plays a key role in fluid balance and other bodily systems; blood levels are largely regulated by the kidneys.
High blood sodium is more common in the elderly, largely because kidney function and the thirst mechanism decline with age, impairing fluid balance. High blood sodium can be both a cause and an effect of health problems.
Anything that causes excessive loss or retention of body water can result in abnormal blood sodium levels. That includes severe diarrhea or vomiting or protracted heavy sweating, especially if followed by the consumption of lots of water but inadequate sodium, as can happen with marathoners running in the heat. Certain medications (notably those that make you urinate more, such as diuretics), as well as kidney or thyroid disease, heart failure, and other disorders can cause abnormal blood sodium levels.
If you get a blood test revealing either a high (or low) level of sodium in the blood, your health care provider will have to evaluate these results with regard to your particular clinical situation and medical history to determine the cause and, therefore, the treatment.