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SOURCE

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Source: Flurie RW, Brophy DF. Disorders of potassium and magnesium homeostasis. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 10th ed. New York, NY: McGraw-Hill; 2017. http://accesspharmacy.mhmedical.com/content.aspx?bookid=1861&sectionid=134127639. Accessed March 31, 2017

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DEFINITION

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  • Serum potassium >5.0 mEq/L (>5.0 mmol/L)

    • Mild: serum potassium 5.1–5.9 mEq/L (5.1–5.9 mmol/L)

    • Moderate: serum potassium 6.0–7.0 mEq/L (6.0–7.0 mmol/L)

    • Severe: serum potassium >7.0 mEq/L (>7.0 mmol/L)

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ETIOLOGY

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  • Develops when potassium intake exceeds excretion or when transcellular distribution of potassium is disturbed.

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PATHOPHYSIOLOGY

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  • Increased potassium intake (eg, use of salt substitutes by dialysis patients containing 10–15 mEq (10–15 mmol) potassium per gram)

  • Decreased renal potassium excretion.

    • Kidneys excrete 80% of daily potassium intake.

    • Potassium retained in acute kidney injury (AKI) or with chronic kidney disease (CKD).

    • Hyperkalemia results from dose-dependent drug effects on kidney regulation:

      • Angiotensin-converting enzyme inhibitors (ACEIs)

      • Angiotensin-II receptor blockers (ARBs)

      • Potassium-sparing diuretics.

      • Prostaglandin inhibitors (eg, nonsteroidal anti-inflammatory drugs [NSAIDs])

  • Tubular unresponsiveness to aldosterone.

  • Redistribution of potassium to extracellular space.

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EPIDEMIOLOGY

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  • Less common than hypokalemia.

  • Incidence in hospitalized patients: 1.4–10%

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PREVENTION

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  • Dietary potassium restrictions for patients with stages 4 or 5 CKD and dialysis patients.

  • Use ACEIs, ARBs, potassium-sparing diuretics and NSAIDs cautiously in patients with underlying heart or liver failure or CKD.

    • Monitor serum potassium within 1 week of drug initiation or dosage increase.

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RISK FACTORS

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  • Age: more common in elderly patients with renal insufficiency.

  • Acute and chronic kidney disease.

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CLINICAL PRESENTATION

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SIGNS AND SYMPTOMS
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  • Often asymptomatic; may be nonspecific and related to muscular or cardiac function.

  • Muscle weakness.

  • Fatigue.

  • Palpitations.

  • Electrocardiogram (ECG) changes include:

    • Peaked T wave.

    • Widened PR interval and QRS complex.

    • Loss of P wave.

    • Sine-wave appearance.

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DIAGNOSIS

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MEANS OF CONFIRMATION AND DIAGNOSIS
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  • Serum potassium >5.0 mEq/L (>5.0 mmol/L)

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LABORATORY TESTS
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  • Metabolic panel.

    • Serum potassium.

    • Serum creatinine.

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DIAGNOSTIC PROCEDURES
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  • ECG

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DIFFERENTIAL DIAGNOSIS
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  • Diabetes mellitus.

  • Rhabdomyolysis.

  • Tumor lysis syndrome.

  • Hemolysis.

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DESIRED OUTCOMES

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  • Antagonize adverse cardiac effects.

  • Reverse signs and symptoms.

  • Return serum and total-body stores of potassium to normal.

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TREATMENT: GENERAL APPROACH

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  • Determined by severity of hyperkalemia, rapidity of development and patient’s clinical condition (Figure 1)

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FIGURE 1.

Treatment approach for hyperkalemia. Serum potassium of 5 mEq/L equivalent to 5 mmol/L. Reprinted with permission from Wells BG, DiPiro JT, Schwinghammer TL, et al. Pharmacotherapy Handbook. 10th ed. New York, NY: McGraw-Hill; 2017.

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