When a kidney function test is done to check kidney health, the report shows creatinine, urea and sometimes electrolytes like sodium, and an abnormal sodium value should not be ignored.
Why sodium is checked in kidney tests
Sodium is an important electrolyte found in the fluid outside the body's cells. It plays a role in the distribution of water in the body, blood pressure and the normal functioning of nerves and muscles. Healthy kidneys help retain sodium and water in the body as needed or remove them through urine. Checking sodium in a kidney function test or related blood test gives the doctor information about the body's fluid balance and electrolyte balance. This can be especially useful in people who have kidney disease, dehydration, vomiting or diarrhoea, or any problem that can affect the balance of water and electrolytes in the body. Note that it is not necessary for every lab's KFT panel to include sodium; at some places it is checked under an electrolyte panel, a basic metabolic panel or a comprehensive metabolic panel. To assess kidney function, doctors usually also look at results like creatinine, eGFR and, where needed, urine albumin.
What is the normal sodium range
In adults, the normal blood sodium level is generally considered to be 135 to 145 mEq/L, which can also be expressed in mmol/L. However, different laboratories' reference ranges can differ slightly, so it is important to also look at the range given on your own report. Below 135 mEq/L is low sodium, called hyponatremia. From 135 to 145 mEq/L is the normal sodium level. Above 145 mEq/L is high sodium, called hypernatremia. Even if the sodium level is slightly outside the normal range, the report is interpreted together with the person's symptoms, medical history, medicines and other tests. For example, if blood sugar is very high, the measured sodium value can appear low. So treatment should not be started on the basis of a single number alone.
Low sodium, hyponatremia symptoms
When blood sodium falls below 135 mEq/L, the condition is called hyponatremia. Its symptoms can include feeling tired and weak, headache or nausea, cramps in the muscles, and difficulty concentrating or thinking. In a severe condition there can be confusion, seizures or unconsciousness. When sodium falls, the tendency of water to enter the body's cells can increase. In severe cases, swelling in the brain's cells can occur, causing neurological symptoms. The severity of symptoms depends on how low the sodium is and how fast it has fallen.
High sodium, hypernatremia symptoms
When the sodium level goes above 145 mEq/L, it is called hypernatremia. Its symptoms can include feeling extremely thirsty, weakness and restlessness, twitching in the muscles, and confusion or abnormal behaviour. In a severe condition there can be seizures or unconsciousness. When sodium rises, there is often a lack of water in the body, though other causes are also possible. If there is sudden confusion, seizures or unconsciousness, emergency medical help should be sought at once.
What an abnormal value does not mean
A low or high sodium level in a KFT report can be a sign of water and electrolyte imbalance. Behind it there can be causes like dehydration, vomiting or diarrhoea, some medicines, hormonal problems or diseases of the kidney and other organs. However, an abnormal sodium value does not always mean the kidneys have failed. To know the correct cause, doctors evaluate other tests and symptoms along with the report. Timely testing and proper treatment can help reduce the risk of serious complications.
