What is hyponatremia (low sodium level in the blood)?
Hyponatremia is when the level of sodium in your blood is lower than normal. Sodium is quite an important mineral that helps balance the amount of fluid (water) in your body. It also helps your nerves and muscles to work as they should.
When the sodium level in your blood is way too low, extra water moves into your cells and makes them swell (get bigger). This can become quite dangerous, especially if it happens in the brain, where there’s not a lot of room to expand.
The kidney connection
Your kidneys play a huge role in keeping your saltiness and fluid levels as balanced as they can get. People with more advanced stages of chronic kidney disease (CKD) might have a harder time balancing their fluid and blood sodium levels. This can also lead to hyponatremia.
Signs and symptoms
The wide majority of people with mild hyponatremia might not show any symptoms. If symptoms are there, they usually show up when the level of sodium in your blood goes very low or drops at a rapid pace. These symptoms include:
- nausea and vomiting
- headache
- muscle weakness, spasms, cramps
- low blood pressure
- dizziness when standing up
- low energy or fatigue
- loss of appetite
- restlessness and bad temper
There are other, more serious symptoms, that can show up in severe cases when the level of sodium in your blood is extremely low. Some of them include:
- altered mental status (extreme confusion)
- hallucinations
- decreased consciousness
- seizures
- coma
Causes
One of the most common reasons for hyponatremia is having way too much fluid (water) in the body. This dilution (watering down) effect on the blood makes the amount seem quite low. Another common cause is when your body loses too much sodium in the urine or even in the sweat.
Do you want to know an interesting fact? In most cases, hyponatremia (low blood sodium) is closely related to how much fluid (water) is in your body than not getting enough sodium in your diet.
There’s a wide range of reasons as to why your water and sodium levels can be out of balance. Some of these reasons are more common for people living with kidney disease, and they include:
- acute kidney injury (AKI), advanced stages of chronic kidney disease (CKD), and kidney failure: the kidneys have a hard time getting rid of extra fluid from the body which also dilutes the blood;
- Thiazide diuretics (water pills), like hydrochlorothiazide (HCTZ) or chlorthalidone: it might cause the body to get rid of too much sodium in the urine (especially in higher doses)
- heart failure: extra fluid can easily build up in the body and dilute the blood
- severe vomiting and diarrhea: it can cause a lot of sodium and fluid loss
- polydipsia (excessive thirst): it can cause a person to drink too many fluids and dilute the blood.
Other well-known causes of hyponatremia that might not be directly linked to kidney disease include:
- extreme hyperglycemia (extremely high blood sugar): extra fluid can build up in the blood to counteract the high level of sugar
- cirrhosis (advanced liver disease): extra fluid can build up in the body and slowly dilute the blood
- syndrome of inappropriate antidiuretic hormone secretion (SIADH): a medical condition where your body holds on way too much water and removes too much sodium in the urine
- medications, like antidepressants, seizure medicines, and cancer medicines: might cause your body to hold extra water and lose a lot of sodium in urine or sweat.
Complications
Hyponatremia that develops slowly in time and is only mildly decreased is not likely to cause any complications, especially when treated properly. On the other hand, sudden hyponatremia (dramatic drop in less than 48 hours) and decreased sodium levels might cause serious issues if left untreated, such as:
- rhabdomyolysis (life-threatening muscle breakdown)
- altered mental status (severe confusion)
- seizures
- coma
- death
Diagnosis
Tests
A simple blood test is generally used to measure the level of sodium in your blood. A normal blood sodium level is somewhere between 135 and 145 milliequivalents/liter (mEq/L). In this case, hyponatremia is when the level of sodium in your blood is below 135 mEq/L. But you need to remember, a low sodium level might come as a consequence for many things.
Your healthcare professional will probably order other tests and ask you questions about your medical history and recent routine to get a full picture. Other tests could also include serum creatinine, glucose (sugar), potassium, carbon dioxide, triglycerides, and urine tests. When looked at together, your healthcare professional might provide you with custom guidance for resolving the issue.
A blood test might help your doctor check for low sodium levels. Even if you don’t present symptoms of low blood sodium, your doctor might order a basic metabolic panel. This tests
Treatment
Treatment is based on the cause and severity of your hyponatremia. Sodium levels fall just below 135 mEq/L, and might not warrant treatment – a closer follow-up and a recheck might be all that’s needed. Prompt treatment is even more important for people who have sudden hyponatremia (dramatic drop in less than 48 hours), and severely decreased levels.
Hyponatremia treatment is customized depending on the patient and requires constant medical supervision. Don’t attempt any treatment approaches on your own without taking to a specialized healthcare professional first.
Your healthcare professional could recommend one or more of these treatments:
- focus on the conditions that cause hyponatremia, like heart failure, cirrhosis, diabetes, and even kidney failure;
- lower the amount of liquids you eat or drink (also known as fluid restriction);
- adjust your medication dose and switch to a completely different medication (if the hyponatremia is a medication side effect);
- adjust your dialysis settings to slow down fluid levels with each session (if you’re on dialysis);
- give a dose of sodium through the veins (intravenous or IV);
- add a type of medication that helps your body remove extra water while also holding on to sodium, like tolvaptan or conivaptan (commonly known as aquaretics);
- add more salt (sodium) to your diet (not a common approach for people with kidney disease).
Prevention for hyponatremia
Keeping your water and electrolyte levels as balanced as you can might help prevent low blood sodium. If you are an athlete, it’s fairly important to drink the proper amount of water during exercise.
You might also want to consider drinking rehydration beverages. These drinks also contain electrolytes and help replenish sodium lost through sweating. These drinks are quite helpful if you lose a lot of fluids through vomiting and diarrhea.
Staying hydrated enough all day long might help manage any wild swings in blood sodium. When you are adequately hydrated, your urine will be pale yellow or clear, and you won’t feel any thirst.
It’s very important to increase your fluid intake if:
- the weather is getting warmer;
- you are at a high altitude;
- you are pregnant or breastfeeding;
- you are vomiting;
- you have diarrhea;
- you have fever
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