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Throughout the body, electrolytes are involved in numerous metabolic and homeostatic processes. Abnormalities are associated with excessive or reduced intake, altered absorption and excretion, or changes in hormonal and neurological homeostasis. Signs and symptoms of electrolyte disorders range from asymptomatic to life-threatening, depending on the speed of onset and degree of electrolyte loss or excess. The goals of therapy for electrolyte disorders are to prevent the development and/or treat life-threatening complications, identify and treat the underlying cause of the disturbance, correct concomitant abnormal electrolyte findings, and attain a normal electrolyte concentration while preventing overcorrection. The rapidity of development, severity of symptoms present, concomitant medical conditions, medications, dietary factors, and considerations for patient compliance should all be considered when selecting a treatment strategy. This chapter provides a review of the pathophysiology, clinical manifestations, and treatment of the most common electrolyte disorders. Listed in Table 34-1 are the normal serum concentrations of the common electrolytes.

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TABLE 34-1 Electrolyte Serum Concentrations
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General Overview

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Sodium is the major extracellular cation and responsible for the majority of the extracellular fluid osmolality. Under normal conditions, the serum sodium concentration is kept between 135 and 145 mEq/L. Disorders of sodium balance are the most common electrolyte disturbances encountered in clinical practice and occur in both inpatient and ambulatory patients.1 Hyponatremia can be classified by the patient's serum osmolality and volume status (Figure 34-1).2 Hypernatremia always causes hypertonicity, and can be classified by the patient's volume status (Figure 34-2).2 Common causes of sodium disorders are listed in Table 34-2.

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Figure 34-1
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Diagnosis of hyponatremia.

Reprinted with permission from Coyle JD, Joy MS. Disorders of sodium and water homeostasis. In: DiPiro JT, Talbert RL, Yee GC, et al, eds. Pharmacotherapy: A Pathophysiologic Approach. 7th ed. Available at: http://www.accesspharmacy.com/content.aspx?aID=3183025.

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Figure 34-2
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Diagnosis of hypernatremia.

Reprinted with permission from Coyle JD, Joy MS. Disorders of sodium and water homeostasis. In: DiPiro JT, Talbert RL, Yee GC, et al, eds. Pharmacotherapy: A Pathophysiologic Approach. 7th ed. Available at: http://www.accesspharmacy.com/content.aspx?aID=3183025.

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TABLE 34-2 Causes and Contributing Factors for Electrolyte Disorders

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