Hyponatremia is a condition in which the blood level of sodium is too low. It is among the most common electrolyte disorders.
What is hyponatremia?
Hyponatremia is when the sodium level is too low. This results in a decreased concentration of sodium ions in the blood. Thus, the concentration drops to values below 135 mmol/l. In severe cases, even life-threatening hyponatremia attacks are possible, which require immediate treatment in a hospital. Hyponatremia is one of the most common electrolyte disorders. It is seen in 15 to 30 percent of all patients undergoing inpatient therapy. The presence of hyponatremia prolongs the patient’s hospital stay by worsening his or her clinical prognosis. However, athletes can also be affected by the electrolyte disorder if they consume an extremely large amount of fluid before a competition. There are several forms of hyponatremia: these are hypovolemic, normovolemic as well as hypervolemic hyponatremia. In the case of hypovolemic hyponatremia, the increase in sodium concentration is accompanied by a reduced blood volume. A typical identifying feature is lower central venous pressure, which is manifested by empty neck veins. Normovolemic hyponatremia is when blood volume is normal with the increased sodium concentration. Hypervolemic hyponatremia is a combination of increased sodium concentration and reduced blood volume. In this case, the central venous pressure increases.
Causes
Hyponatremia is initially thought to be caused by a deficiency of sodium. However, the electrolyte disturbance is triggered by a relative excess of water in the body. In this process, the organism no longer excretes pure water properly through the kidneys. In relation to the sodium concentration in the body, the excess of water in the blood proves to be too high. The volume of the extracellular fluid is determined by the solution water of the sodium ions as well as their counterions such as chloride. In contrast, potassium is predominant in the intracellular fluid. In the event of a rapidly occurring sodium deficiency, there is a drop in oncotic pressure. The water now flows into body cells, in which there is initially a higher oncotic pressure, resulting in an increase in cell volume. This in turn can lead to an increase in pressure in the brain. The symptoms of the disease then correspond to the symptoms that occur with increased intracranial pressure. However, if hyponatremia develops slowly, this does not occur. The most common triggers for hyponatremia are considered to be excessive drinking of water, water overload due to gastric lavage, psychogenic polydipsia, the use of certain medications such as diuretics or ACE inhibitors, as well as severe diarrhea and renal salt loss. However, conditions such as hypopituitarism, hypothyroidism, or adrenocortical insufficiency are also possible culprits.
Symptoms, complaints, and signs
One problem with hyponatremia is its nonspecific symptoms, which not infrequently lead to misdiagnosis. These include muscle cramps, seizures, lethargy, loss of appetite, confused behavior, and disorientation. Even coma is within the realm of possibility. Rapidly progressing hyponatremia results in cerebral edema. This is noticeable by tremors, nausea, headaches and epileptic seizures. If, on the other hand, the electrolyte disturbance occurs slowly, the patient initially suffers from confusion and fatigue for two days. There are also changes in his personality. If the hyponatremia takes a chronic course, gait disturbances and frequent falls often occur. Because the electrolyte disturbance also negatively affects bone mineralization, there is a tendency to bone loss (osteoporosis), which in turn increases the risk of bone fractures.
Diagnosis and disease progression
Hyponatremia is most commonly diagnosed by determining the serum sodium level. Urine osmolality, serum osmolality, extracellular volume status, and urine sodium concentration are considered other important parameters. Determination of these parameters must be done as soon as possible. Exclusion diagnostics also play an important role. Thus, it is important to rule out other diseases that may be responsible for the symptoms.These may be diseases of the kidneys or thyroid gland. The course of hyponatremia depends on the extent of electrolyte disturbance. In severe cases, complications such as central pontine myelinolysis, in which the sheathing of nerve fibers within the brainstem is damaged, may occur.
Complications
Hyponatremia can cause a variety of symptoms. The complications and symptoms usually depend on the actual level of sodium in the blood and may vary for this reason. The patient usually feels ill and suffers from a loss of appetite. Furthermore, the affected person appears confused and is unable to concentrate and coordinate properly. The muscles ache and it is not uncommon for cramps and nausea to occur. In the further course of hyponatremia, the patient may also experience epileptic seizures and severe headaches. It is also not uncommon for gait disturbances and fatigue to occur. The patient is also no longer able to work under pressure and feels fatigued. The patient’s quality of life is considerably reduced by hyponatremia. Treatment of hyponatremia is always causal and depends on the underlying disease. As a rule, no further complications occur. The symptoms can be remedied with the help of solutions and infusions. If the affected person also suffers from heart complaints, these are treated. In most cases, the further course of the disease depends on the cause of the hyponatremia.
When should one go to the doctor?
If symptoms such as muscle cramps, seizures, and lethargy are noticed, hyponatremia may be underlying. A visit to the doctor is indicated if symptoms persist for more than a week or recur at intervals of a few months. Medical advice is required at the latest when further symptoms occur. Nausea and vomiting, headaches and changes in behavior must be clarified immediately. If tremor attacks or epileptic seizures occur, friends and relatives or the affected person himself must call the emergency doctor. In severe cases, first aid must be administered until the doctor arrives. Other warning signs that require clarification are fatigue, confusion and gait disturbances. Frequent bone fractures also indicate hyponatremia and should be evaluated by a physician. Individuals who have been diagnosed with sodium deficiency are particularly susceptible to developing hyponatremia. If the above signs occur after excessive consumption of water, gastric lavage, or in the setting of psychogenic polydipsia, medical advice is needed. People who regularly take diuretics or ACE inhibitors should inform their physician of any unusual symptoms.
Treatment and therapy
Treatment of hyponatremia depends on the form and cause of the electrolyte disturbance. If hypovolemic hyponatremia is present, volume substitution with isotonic NaCI solution takes place. If, on the other hand, it is the normovolemic form, there is a partial and slow administration of sodium. In the case of hypervolemia, the supply of water to the patient’s body is limited. In some cases, the administration of saline may also be useful. This is done either through the gastrointestinal tract or as an infusion. To avoid central pontine myelinolysis, it is important to balance sodium levels slowly and carefully. Regular laboratory tests are required for this purpose. In cases of mild hyponatremia, it is often sufficient to discontinue medications such as thiazide diuretics. In addition, it also helps to treat heart failure or to restrict excessive water intake, which depends on the triggering cause in each case. In the case of hypervolemic hyponatremia, a combination of saline and loop diuretics is sometimes helpful. Hemofiltration may need to be performed in some patients.
Prevention
Athletes can prevent hyponatremia by avoiding drinking too much water before a competition. It is considered reasonable during a competition to drink 150 to 300 milliliters of water every 15 to 20 minutes, which is equivalent to a small cup.
Aftercare
After treatment for hyponatremia, it is important for patients to learn about prophylaxis and aftercare options. The condition often occurs in combination with too much water intake. Follow-up care is therefore about consciously paying attention to the amount of water drunk.This is the only way for sufferers to control their electrolyte balance. Those who suffer from the condition more frequently can minimize the risk by resorting to dietary supplements containing sodium. Doctors prescribe these agents and provide patients with precise dosage instructions. Those affected should also adhere to these so that they take the correct amount. These supplements are also available over the counter in pharmacies and drugstores. However, for individualized follow-up care, patients should always talk to their doctor to avoid dosage errors. Depending on the cause of the disease, follow-up care may also extend to follow-up therapy for the underlying disease. This often includes follow-up examinations in connection with kidney complaints or with cardiovascular complications. Following an acute disease state, short-term solutions tend to be used. Longer-term follow-up treatments usually do not play a role. Sufferers should still remember to monitor their sodium intake.
Here’s what you can do yourself
Hyponatremia can be prevented in many cases. If the affected person is an athlete, it is advisable to take in water in not too large quantities before competitions. It is better to drink 200 milliliters of water every 20 minutes in order to maintain a balanced electrolyte balance. In most cases, this corresponds to an ordinary cup of water. In treating hyponatremia, sufferers can limit it by taking sodium in the form of supplements. In doing so, these can be prescribed by a doctor or purchased directly from a drugstore or pharmacy. However, the patient should always consult with the doctor to avoid taking in too much sodium. If the condition has other causes, treatment of the underlying condition is the first step in most cases. Since those affected often suffer from kidney problems or heart problems due to hyponatremia, these organs should be examined regularly. This can prevent further complications. Furthermore, hyponatremia in acute conditions can be treated by limiting water intake. However, this should not be a long-term treatment method.
