Hyponatremia is an electrolyte disturbance in which the sodium concentration in the serum is lower than normal. Sodium is the dominant extracellular cation and cannot freely cross the cell membrane. Its homeostasis is vital to the normal physiologic function of cells. Normal serum sodium levels are between 135-145 mEq/L. Hyponatremia is defined as a serum level of less than 135 mEq/L and is considered severe when the serum level is below 125 mEq/L.
Hyponatremia is most often a complication of other medical illnesses in which either fluids rich in sodium are lost (diarrhea or vomiting) or excess water accumulates in the body at a higher rate than can be excreted (syndrome of inappropriate antidiuretic hormone,polydipsia).Symptoms of hyponatremia include nausea and vomiting, headache, confusion, lethargy, fatigue, appetite loss, restlessness and irritability, muscle weakness, spasms, or cramps, seizures, and decreased consciousness or coma.
Cerebral salt-wasting syndrome is a rare endocrine condition featuring hyponatremia and dehydration in response to trauma/injury or the presence of tumors in or surrounding the brain. This form of hyponatraemia is due to excessive renal sodium excretion resulting from a centrally mediated process.CSWS is a diagnosis of exclusion and may be difficult to distinguish from the syndrome of inappropriate antidiuretic hormone (SIADH).
Hypernatremia is an electrolyte disturbance that is defined by an elevated sodium level in the blood.Clinical manifestations of hypernatremia can be subtle, consisting of lethargy, weakness, irritability, and edema. With more severe elevations of the sodium level, seizures and coma may occur.Severe symptoms are usually due to acute elevation of the plasma sodium concentration to above 158 mEq/L.