What is Sodium Imbalance ?
Sodium is the major cation (90%) in extracellular fluid (ECF). It's the main factor responsible for ECF concentration. Increases or decreases in ECF sodium concentrations greatly affect ECF volume and distribution. Sodium controls the distribution of water throughout the body and regulates ECF volume. It also plays an important role in the transmission of nerve impulses and muscle contraction.
Hyponatremia is an excess of body water relative to sodium; it isn't synonymous with sodium depletion. Sodium loss is just one state in which hyponatremia can occur. Hypernatremia is a deficit of body water relative to sodium. Thirst seems to be the major defense mechanism against hypernatremia.The body requires only 2 to 4 g of sodium per day, but most Americans consume 6 to log per day (mostly sodium chloride, as table salt) and excrete excess sodium through the kidneys and skin. Under the influence of antidiuretic hormone (ADH) and aldosterone, the kidneys primarily regulate ECF sodium balance.
Causes of Sodium ImbalanceLow sodium levels "hyponatraemia" are caused by:
High sodium levels "hypernatraemia" are caused by:
Signs & Symptoms of Sodium Imbalance
Many of the clinical features of hyponatremia relate to brain swelling and cerebral edema. The development and severity of symptoms is also related not only to the degree of hyponatremia, but also the rate at which the sodium concentration in the body is changing. Common signs and symptoms of salt imbalance include:
Serum sodium levels are less than 135 mEq/L with hyponatremia and greater than 145 mEq/L with hypernatremia.Additional laboratory studies are used to determine the etiology of the imbalance and differentiate between a true deficit and an apparent deficit due to sodium shift or to hypervolemia or hypovolemia.
When possible, patients with sodium deficits receive oral sodium supplementation. Therapy for mild hyponatremia associated with hypervolemia usually consists of restricted water intake. If fluid restriction alone fails to normalize serum sodium levels, demeclocycline or lithium, which blocks ADH action in the renal tubules, can be used to promote water excretiop.
In extremely rare instances of severe symptomatic hyponatremia, when serum sodium levels fall below 110 mEq/L, treatment may include infusion of 3% or 5% sodium chloride solution.Treatment with an infusion of hypertonic saline solution requires careful patient monitoring in an intensive care setting for signs of circulatory overload, which is potentially fatal. (Administration of hypertonic saline solution causes water to shift out of celIs. risking intravascular volume overload.) For this reason, furosemide is usually administered concurrently. The hypertonic saline solution is infused slowly, in small volumes.
If indicated, treatment must include correction of the underlying disorder; for example, hormonal therapy may be needed to treat endocrine disorders.
Primary treatment for hypernatremia associated with water deficit includes slow, oral replacement of the water deficit to stop the water loss. If the patient can't tolerate oral replacement, treatment requires I.V. administration of salt-free solutions (such as dextrose in water) to return serum sodium levels to normal, followed by infusion of half-normal saline solution to prevent hyponatremia.
ALERT: Hypernatremia must be corrected slowIy, over about 2 days, to avoid shifting water into brain cells, resulting in cerebral edema. Some clinicians recommend infusion of a hypotonic solution, such as 0.3% sodium chloride, to permit a more gradual lowering of serum sodium levels. reducing the risk of cerebral edema.Other treatment measures may include restricted sodium intake for patients with sodium gain. Diuretics may be given to increase sodium loss in combination with oral or I.V. water replacement.
A person can take these actions to help prevent salt imbalance:
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