Skip to Main Content

Instructors can request access to the Casebook Instructor's Guide on AccessPharmacy. Email User Services ( for more information.


After completing this case study, the reader should be able to:

  • Analyze a patient case history and identify potential causes of electrolyte disorders.

  • Select the appropriate route of administration and dose of electrolyte replacement therapy specific for a patient.

  • Develop a monitoring plan for efficacy and toxicity in patients receiving electrolyte replacement therapy.

  • Outline a patient education plan for a patient receiving electrolyte replacement supplements.


Chief Complaint

“I’m short of breath.”


Dorothy Snow is a 45-year-old woman with a history of nonischemic cardiomyopathy who presents to the ED with a 3-day history of shortness of breath with mild to moderate exertion. She reports three-pillow orthopnea × 2 days and cough during sleep. Denies chest pain; occasional palpitations. She has some stomach discomfort that she notices after taking her potassium supplement. She reports a 10-lb weight gain in the past week and an increase in her lower extremity edema.

Two months ago, Mrs Snow was hospitalized briefly with atypical chest pain and had persistent hypokalemia for which her metolazone 5 mg daily was discontinued. Approximately 1 month ago, shortly after Thanksgiving, she subsequently developed significant fluid retention and her PCP restarted metolazone 5 mg PO MWF. About 2 weeks ago, she had an ED visit and her potassium was 7.2 mEq/L (hemolyzed sample). The potassium level was repeated with a result of 5.5 mEq/L. At that time, her potassium supplement dose was reduced from 80 mEq PO QID to 80 mEq PO BID.

PMH (Per Patient Report and Medical Records)

Nonischemic cardiomyopathy—echo LVEF 25% (11 months ago)

ICD placement 2 months ago



Sleep apnea

Type 2 DM with peripheral neuropathy


Chronic sinusitis

Anxiety disorder



Both parents are deceased.


Lives with husband. No alcohol use. Former smoker—quit 8 years ago. No illicit drugs.


Candesartan 32 mg PO daily

Omeprazole 20 mg PO daily

Carvedilol 25 mg PO BID

Digoxin 0.25 mg PO daily

Spironolactone 25 mg PO daily

Furosemide 80 mg PO BID

Citalopram 20 mg PO daily

Atorvastatin 20 mg PO daily

Metformin 1000 mg PO BID

Pregabalin 50 mg PO BID

Metolazone 5 mg PO ...

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.