Study Points

Hypokalemia and Hyperkalemia

Course #34643 - $15 • 3.5 Hours/Credits

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    • Review your Transcript to view and print your Certificate of Completion. Your date of completion will be the date (Pacific Time) the course was electronically submitted for credit, with no exceptions. Partial credit is not available.
  1. What percent of total body potassium is in the extracellular fluid?

    DEFINITION AND EPIDEMIOLOGY

    The amount of potassium present in the average human body is approximately 50 mEq/kg. Of this, 90% is found in intracellular fluid, 8% in skin and bones, and 2% in extracellular fluid [1,2,3,4,5]. The maintenance of this relatively small amount of extracellular potassium is critical; small changes can cause serious clinical consequences.

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  2. Severe hyperkalemia is defined as a serum level of

    DEFINITION AND EPIDEMIOLOGY

    Chronic hypokalemia and hyperkalemia develop in a minimum of weeks to months, and acute hypokalemia and hyperkalemia occur over hours to days. Mild hypokalemia occurs at serum levels of less than 3.5 mEq/L, but greater than 3 mEq/L; moderate hypokalemia at 2.5–3 mEq/L; and levels less than 2.5 mEq/L are considered severe [7,8]. Mild-to-moderate hyperkalemia is defined as a serum level of 5.5–6.9 mEq/L, and severe hyperkalemia is a serum level of 7 mEq/L or greater [9]. Physician consultation is indicated for serum potassium levels less than 3 mEq/L or greater than 6 mEq/L.

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  3. The main cause of hypokalemia is

    DEFINITION AND EPIDEMIOLOGY

    In the vast majority of cases, hypokalemia is drug induced; approximately 20% to 50% of all patients who are treated with non-potassium-sparing diuretics develop low serum potassium levels [7,9]. Other populations with a high incidence of hypokalemia include individuals who have undergone bariatric surgery and those with eating disorders, acquired immune deficiency syndrome (AIDS), and/or alcohol use disorder [10]. The incidence of hyperkalemia in the pediatric population is unknown, though it can exceed 50% in extremely low birth weight premature infants [9]. Most cases of chronic hyperkalemia are caused by renal failure; however, the increased use of spironolactone after the publication of the Randomized Aldactone Evaluation Study has resulted in a marked increase in morbidity and mortality from hyperkalemia, with an estimated 50 excess hospital admissions per 1,000 additional prescriptions for spironolactone [11,12]. Careful surveillance of potassium and creatinine may improve survival in patients with severe heart failure being treated with spironolactone [13,14].

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  4. Hyperkalemia is caused by

    PATHOPHYSIOLOGY

    As noted, hyperkalemia is caused by excessive intake, impaired elimination, or increased shift of potassium from intracellular to extracellular space (Table 2). Excessive intake of potassium causing hyperkalemia is rarely seen in patients with normal renal function. Nonetheless, patients taking large doses of over-the-counter potassium supplements (often labeled "for heart health") may indeed present with clinically significant hyperkalemia. Usually, ingestion of potassium only causes significant elevation in patients with low glomerular filtration rates (GFRs).

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  5. Which of the following conditions can cause hyperkalemia?

    PATHOPHYSIOLOGY

    POSSIBLE CAUSES OF HYPERKALEMIA

    Renal failure
    Hypoaldosteronism
    Type 4 renal tubular acidosis
    Adrenal insufficiency (Addison disease)
    Sickle cell anemia
    Systemic lupus erythematosus
    Insulin deficiency
    Certain medications
    Acidosis
    Familial hyperkalemic periodic paralysis
    Rhabdomyolysis
    Tumor lysis syndrome
    Traumatic venipuncture (pseudohyperkalemia)
    Severe leukocytosis (pseudohyperkalemia)
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  6. Which of the following drugs is NOT known to induce hyperkalemia?

    PATHOPHYSIOLOGY

    MEDICATIONS THAT MAY INDUCE HYPERKALEMIA

    Angiotensin-converting enzyme (ACE) inhibitors
    Potassium-sparing diuretics (e.g., spironolactone, amiloride)
    Nonsteroidal anti-inflammatory drugs (NSAIDs)
    Trimethoprim-sulfamethoxazole
    Heparin
    Cyclosporine
    Tacrolimus
    Trimethoprim
    Pentamidine
    Angiotensin receptor blockers (ARBs)
    Direct renin inhibitors
    Beta blockers
    Calcium channel blockers
    Succinylcholine
    Digoxin
    Mannitol
    Potassium tablets
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  7. Which of the following may result in hypokalemia with low urinary potassium?

    DIAGNOSIS

    Occasionally, hypokalemia is not due to increased renal loss; these patients will have low urinary potassium (<20 mEq/L) [5]. The differential diagnosis is fairly limited and generally involves some sort of gastrointestinal loss, through laxative abuse, villous adenoma, or severe diarrhea [5]. Patients previously treated with non-potassium-sparing diuretics who are potassium depleted will also have low urinary potassium [5]. Catecholamine excess, whether endogenous (as seen in acute myocardial infarction) or exogenous (as in beta-adrenergic agonist administration), may also cause transient hypokalemia because of an increased cellular uptake of potassium [5].

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  8. Emergency treatment of a patient with a potassium level of 7 mEq/L who has developed ECG changes (QRS widening and bradycardia) and muscle weakness is usually

    MANAGEMENT

    Treatment of hyperkalemia involves the following principles and practice, many of which occur parallel to each other. First, the patient should have an ECG to evaluate for toxicity and should be placed on a monitor, if warranted [9]. If the patient does have ECG changes, consider hospitalization if still in the outpatient setting. Next, identify sources of potassium intake and eliminate if possible. Consider whether to initiate a plan to shift potassium from the extracellular to the intracellular. Lastly, increase potassium excretion if needed for either short-term or long-term management [17].

    Treatment of acute hyperkalemia with life-threatening symptoms (generally seen with potassium levels ≥7 mEq/L) is accomplished by the administration of IV calcium [2,3,4]. The usual recommended dose is 10 mL of a 10% calcium solution, such as calcium chloride [9,18]. The ECG should be monitored while calcium is administered, and calcium should be administered only when ECG changes, such as a widening QRS, have occurred [3,4]. Calcium does not correct the underlying hyperkalemia; it only counters the adverse neuromuscular effects [4]. Calcium infusion should always be followed by specific therapy aimed at lowering the plasma potassium level (e.g., insulin and glucose infusion) [9].

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  9. Which of the following foods has the greatest potassium content?

    MANAGEMENT

    POTASSIUM CONTENT IN COMMON FOODS

    FoodPotassium Content
    French fries (5 ounces)17.7 mEq
    Potato chips (1.5 ounces)10.2 mEq
    Banana (small)8.6 mEq
    White mushrooms (2.5 ounces)8.1 mEq
    Orange juice (7 ounces)7.9 mEq
    Whole milk (7 ounces)7.7 mEq
    Cooked broccoli (2.5 ounces)5.8 mEq
    Blueberries (3.5 ounces)1.9 mEq
    White chocolate (0.75 ounce)1.8 mEq
    Cooked onions (2.5 ounces)1.5 mEq
    Cola (14 ounces)0.2 mEq
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  10. Type 1 renal tubular acidosis can cause

    SPECIAL TOPICS

    Type 1 RTA is caused by a failure of the distal tubule to secrete acid into the urine, leading to acidosis and hypokalemia. Diagnostic workup will reveal alkalotic urine and possibly metabolic acidosis. (Renal excretion of uric acid and bicarbonate is the primary homeostatic mechanism of the body for maintaining normal pH within a very limited pH range.) Renal and bladder calculi may be seen due to high urine pH, and osteopenia or osteoporosis may develop due to urinary loss of calcium.

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  • Back to Course Home
  • Participation Instructions
    • Review the course material online or in print.
    • Complete the course evaluation.
    • Review your Transcript to view and print your Certificate of Completion. Your date of completion will be the date (Pacific Time) the course was electronically submitted for credit, with no exceptions. Partial credit is not available.