NAPLEX Question of the Week: Hyperkalemia

A potentially life-threatening electrolyte abnormality is the subject of our question of the week.
NAPLEX Question of the Week: Hyperkalemia

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AD is a 73-year-old female who comes into the emergency room overnight complaining of muscle weakness, nausea, vomiting, and shortness of breath. Initial labs show a potassium conentration of 7.1 mEq/L. An EKG also demonstrates peaked T waves. The patient's baseline SCr is 1.2 meq/L and currently is 3.0 meq/L. The medical resident wants to know what agents they should use to treat AD's hyperkalemia. Which of the following agents could potentially be used in the management of  AD's hyperkalemia? Select all that apply. 

A. Albuterol sulfate 10 mg nebulized

B. Calcium gluconate 1 gram IV

C. Furosemide 40 mg IV 

D. Insulin Regular 10 units SQ plus 50mL D50W IV

E. Dexamethasone 4 mg IV





Answers with rationale:

The correct answer is A, B, and C.

Hyperkalemia (elevated potassium concentrations in the blood) is sometimes an emergency that requires prompt treatment due to the risk of developing arrhythmias or sudden cardiac death. While concentrations just above the normal limit (around 5 meq/L) can be managed conservatively, those above 5.5 meq/L with acute renal dysfunction, above 6.5 meq/L, or with EKG changes should be managed emergently.

There are many agents used in the treatment of hyperkalemia. The first agent that should be used is calcium if there are EKG changes. This stabilizes the cardiac membrane and gives the other agents time to work. Our patient has peaked T waves so calcium should be administered making answer choice B is correct. Typically calcium gluconate is given over calcium chloride as the latter is often relegated to code situations due to increased risk of burning/irritation on administration and is preferred to give via central line. 

The next group of agents used in hyperkalemia shift potassium into the cells. These include high-dose albuterol, insulin regular 10 units IV (with dextrose to prevent hypoglycemia), and/or bicarbonate administration. Insulin is the preferred next agent and is given intravenously in hyperkalemia treatment to promote more consistent bioavailability. This makes answer choice D incorrect as this is the wrong route of administration. Albuterol, while a correct option (answer A), is rarely used due to need to administer many nebulized doses to ensure shift of potassium intracellularly which can also have significant tachycardia. 

Lastly, agents to eliminate potassium from the body include loop diuretics or potassium binders such as Kayexalate (sodium polystyrene sulfonate) or Lokelma (sodium zirconium cyclosilicate). In some cases, dialysis may be considered, especially if the patient already is a chronic dialysis patient with access. This makes answer choice C correct. 

A good way to remember which agents can be used is C A BIG K DROP (C-calcium, A-albuterol, B-bicarbonate, IG-insulin with glucose/dextrose, K-Kayexalate, Drop-Diuretics/Dialysis).  Also, remember that any exogenous potassium supplementation should be stopped in patients with hyperkalemia as this is a common reason for inducing it in the first place!

Dexamethasone (brand Decadron) is used in many conditions but is not used specifically for the treatment of hyperkalemia, making answer choice E incorrect. Alsosterone or eplerenone, aldosterone antagonists that "sound" like steroids and are often used in management of heart failure, are also known as potassium-sparing diuretics and can induce hyperkalemia. These should be avoided in patients who have a SCr of 5.5 meq/L or a Clcr of 30ml/min or less. 

NAPLEX Competencies covered:

1.5 – Signs or symptoms of medical conditions, healthy physiology, etiology of diseases, or pathophysiology

2.1 – Pharmacology, mechanism of action, or therapeutic class

3.5 – Drug route of administration, dosage forms, or delivery systems

3.11 – Evidence-based practice

December is here so the studying if hasn't been regular should ramp up quickly! Look forward to helping you toward passing the NAPLEX!

Dr. B

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