Fluid & Electrolyte Q 81

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When assessing a patient for electrolyte balance, the nurse is aware that etiologies for hyponatremia include:

  

    A. Water gain

    B. Diuretic therapy

    C. Diaphoresis

    D. All of the following

    

    

Correct Answer: D. All of the following

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Water gain, diuretic therapy, and diaphoresis are etiologies of hyponatremia. The etiology of hyponatremia can be classified based upon the volume status of the extracellular fluid. Sodium is the major solute of extracellular fluid (ECF). Based upon the volume of ECF, a patient can be classified into hypovolemic, euvolemic, or hypervolemic.

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Option A: Physiological stimuli that cause vasopressin release in adjunct with increased fluid intake can cause hyponatremia. Hypothyroidism and adrenal insufficiency may contribute to an increased release of vasopressin. Physiological stimuli for vasopressin release include loss of intravascular volume (hypovolemic hyponatremia) and the loss of effective intravascular volume (hypervolemic hyponatremia).

Option B: Many drugs cause hyponatremia and the most common include: vasopressin analogs such as desmopressin and oxytocin; medications that stimulate vasopressin release or potentiate the effects of vasopressin such as selective serotonin-reuptake inhibitors and other antidepressants morphine and other opioids; and medications that impair urinary dilution such as thiazide diuretics.

Option C: Water excretion is tightly regulated by antidiuretic hormone (ADH), synthesized in the hypothalamus, and stored in the posterior pituitary gland. Changes in tonicity lead to either enhancement or suppression of ADH secretion. Increased ADH secretion causes reabsorption of water in the kidney, and suppression causes the opposite effect.

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