Hypernatremia causes/symptoms

Hypernatremia (plasma Na >150 mmol/L) is always hyperosmolar, Symptoms of hypernatremia are primarily neurological (because of intraneuronal loss of H2O to the ECF) and include tremors, irritability, ataxia, confusion, and coma. As with hyponatremia, the rapidity of the development of hypernatremia wiU determine the plasma Na value at which symptoms occur. Acute development may cause symptoms when Na reaches 160 mmol/L, although in chronic hypernatremia, overt symptoms may not occur until Na exceeds 175 mmol/L. In chronic hypernatremia, the intracellular osmolality of CNS cells wiU increase to protect against intracellular dehydration. Because of this, rapid correction of hypernatremia can cause dangerous cerebral edema, as CNS cells will take up too much water if the ICF is hyperosmotic when normonatremia is achieved. ... 

Parenteral phosphorus supplementation is associated with risks of hyperphosphatemia, metastatic soft tissue deposition of calcium-phosphate product, hypomagnesemia, hypocalcemia, and hyperkalemia or hypernatremia (caused by intravenous phosphorus salt) (Table 49-9). Inappropriate administration of large doses of parenteral phosphorus over relatively short time periods has resulted in symptomatic hypocalcemia and soft-tissue calcification. The rate of infusion and choice of initial dosage should therefore be based on severity of hypophosphatemia, presence of symptoms, and coexistent medical conditions. Patients should be closely monitored with frequent (every 6 hours) serum phosphorus determinations for 48 to 72 hours after starting intravenous therapy. It may be necessary to continue administration of intravenous phosphorus for several days in some patients, while other patients may be able to tolerate an... 

Symptoms of hypernatremia are primarily caused by decreased neuronal cell volume and can include weakness, restlessness, confusion, and coma. 

Two-thirds of total body water is distributed intracellularly while one-third is contained in the extracellular space. Sodium and its accompanying anions, chloride and bicarbonate, comprise more than 90% of the total osmolality of the extracellular fluid (ECF), while intracellular osmolality is primarily dependent on the concentration of potassium and its accompanying anions (mostly organic and inorganic phosphates). The differential concentrations of sodium and potassium in the intra- and extracellular fluid is maintained by the Na+-K+-ATPase pump. Most cell membranes are freely permeable to water, and thus the osmolality of intra- and extracellular body fluids is the same. Symptoms in patients with hypo- and hypernatremia are primarily related to alterations in cell volume. It is therefore essential to understand the factors that cause changes in cell volume. 

The symptoms of hypernatremia are primarily caused by a decrease in neuronal cell volume, and may include weakness, restlessness, confusion, and coma. Hypernatremia results in movement of water from the intracellular space to the extracellular fluid. Neurons can adapt to hypertonicity in the ECF by generating intracellular organic osmolytes within 24 hours of onset. This increase in intracellular fluid tonicity then draws water into the neurons, thus limiting the decrease in cell volume. Patients with chronic hypernatremia are less likely to present with symptoms caused by this cerebral adaptation. 

A loss of fluid from the body without loss of sodium can lead to hypovolemia and concentration of sodium and hypernatremia. Fluid then is hypertonic and can cause cellular shrinkage owing to fluids moving out of cells in an attempt to balance the hypertonic fluid. The symptoms of fluid imbalance can be accompanied by symptoms of electrolyte imbalance and shifts in other electrolytes that occur in an attempt to balance electrolytes. 

Some symptoms of hypernatremia may vary depending on the underlying cause. If dehydration is present owing to vomiting or diarrhea or failure to drink fluids, the urine output will be low (< 30 mL/h) with dark yellow appearance. However, if a hyperosmotic state or a condition causing decreased ADH release, such as diabetes insipidus, is... 

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