Hyponatremia is an electrolyte condition caused by the deficiency of sodium Na+ ion in the blood plasma. The normal concentration of sodium ion for a normal person is between 136-145 milliequivalent per liter, but if this level reduces below 130 meq/L or lower, the patient may slip into a coma. It is one of the most common electrolyte disorders found in elderly persons. However, it may also affect patients of any age group if the excess of water in relation to salt concentration is not balanced properly.
Sodium ion is distributed within the human body in various percentages. For example, 55% of sodium is found in blood plasma and other extra cellular fluids, 40% is found in bones and the remaining 5% is found in various organs and cells. The amount of sodium found in extra cellular cells is about almost 140 meq/L while only 5 meq/L is found in intracellular cells. The reason behind this uneven distribution of sodium ion is necessary to maintain and regulate blood pressure, conduction of nervous systems along with transporting various nutrients to different parts of the body. During the day, the intestines and the kidneys continuously monitor and regulate the amount of sodium ions depending upon the type of diet that is consumed by the human body. If dietary sodium is excessively high or low, the intestines absorb the sodium while the kidneys excrete equal amounts of urine to balance everything out.
Hyponatremia starts developing when the sodium ion concentration decreases to approximately 105 meq/L. The human body usually applies two different mechanisms to control the level of sodium and water, and they work in combination with each other to regulate blood pressure if it becomes very high or very low. The human circulatory system consisting of arteries, veins and capillaries maintain the level of sodium and water by increasing sodium or decreasing body water. A person may suffer from hyponatremia due to various reasons such as:
- Diseases of the pituitary glands
- Diseases of the kidneys
- Diseases of the hypothalamus
Types of Hyponatremia
There are several different types of hyponatremia that can develop within the human body due to various reasons. These include:
- Hypovolemic Hyponatremia: This is caused when sodium and free water are lost or replaced by some other hypotonic fluids. Sodium can be lost due to either renal or non-renal routes.
- Euvolemic Hyponatremia: The normal level of sodium in the blood serum is maintained but the volume of water exceeds the normal level. This type is commonly found in psychiatric patients.
- Hypervolemic Hyponatremia: The total body sodium and total body water increases abnormally and may lead to renal failure.
- Redistributive Hyponatremia: Water shifts from intracellular to extra cellular compartments giving rise to dilution of sodium levels. However, total body sodium and total body water remains unchanged.
Various Symptoms and Causes of Hyponatremia
Hyponatremia may develop due to excessive loss of dietary sodium or water by the patient. Many blood pressure patients follow a low sodium diet to control their blood pressure levels and this in turn may cause hyponatremia. It may also develop due to excessive sweating during any sports and activities or for those patients whose body fails to regulate the concentrations of various nutrients in the blood stream. This is more frequent in cases of elderly patients who consume diuretics for longer periods of time. Excessive drinking of water or prolonged untreated diarrhea can also cause hyponatremia.
Symptoms: May include headache, fatigue, nausea and muscle cramps. Severe hyponatremia may lead to coma or even death if not treated immediately.
Diagnosis: Hyponatremia can be diagnosed only after carrying out the blood test of serum sodium for its concentrations in the blood.
Treatment: Severe hyponatremia can be treated with 5% injection of sodium chloride in water into the blood stream. Patients are advised to consume less water on a daily basis and more acute cases are to be treated with hormones.
Prevention: Patients who consume diuretic drugs on a regular basis should keep a check on the various symptoms of hyponatremia before it possibly turns fatal.