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CHAPTER SUMMARY FROM THE PHARMACOTHERAPY HANDBOOK
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For the Chapter in the Schwinghammer, Handbook (not Wells Handbook anymore) please go to Chapter 76, Electrolyte Homeostasis.
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KEY CONCEPTS
Potassium regulates many biochemical processes in the body and is a key cation for electrical action potentials across cellular membranes.
The kidney is the primary route of potassium elimination.
In patients with concomitant hypokalemia and hypomagnesemia, it is imperative to correct the hypomagnesemia before the hypokalemia.
Potassium chloride is the preferred potassium supplement for the most common causes of hypokalemia.
Hyperkalemia is a common occurrence in patients with acute kidney injury or chronic kidney disease.
Hypomagnesemia is commonly caused by excessive gastrointestinal or renal magnesium wasting.
Hypermagnesemia is predominantly observed in patients with acute or chronic kidney disease.
Severe hypermagnesemia may affect the neuromuscular and cardiovascular systems.
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Patient Care Process for the Management of Potassium and Magnesium Disorders

Collect
Patient characteristics (eg, age, race, sex)
Patient history (past medical, family, social—dietary habits)
Current medications including over-the-counter medications, herbals, dietary supplements
Subjective data
Objective data
BP, heart rate (HR), height, weight
Labs (eg, basic metabolic panel, calcium, magnesium, phosphorus)
Other diagnostic tests when indicated (eg, ECG, urinalysis, urine electrolytes)
Assess
Presence of symptoms of an electrolyte disorder
Presence of ECG changes (see Fig. 68-1)
Severity of electrolyte disorder (eg, change from baseline value, timing of development of electrolyte disorder)
Kidney function (eg, eGFR, creatinine clearance, presence of chronic kidney disease)
Current medications that may contribute to electrolyte disorder (see Tables 68-1, 68-6, and 68-8)
Current diet that may contribute to electrolyte disorder (see Tables 68-2 and 68-9)
Plan*
Identification of the most likely cause of the electrolyte disorder and discontinuation of offending medication or substance (if applicable)
Dietary modifications (see Tables 68-2 and 68-9)
Drug therapy regimen including specific medication, dose, route, frequency, and duration; specify the continuation and discontinuation of existing therapies (see Tables 68-4, 68-5, and 68-7)
Monitoring parameters including efficacy (eg, potassium, magnesium, SCr), safety (medication-specific adverse effects), and need for repeat or additional drug therapy
Patient education (eg, purpose of treatment, dietary and lifestyle modification, drug therapy)
Referrals to other providers when appropriate (eg, physician, dietician)
Implement*
Follow-up: Monitor and Evaluate
Resolution of electrolyte disorder and prevention of further episodes
Presence of adverse effects
Development/progression of kidney impairment
Patient adherence to treatment plan using multiple sources of information
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Preclass Engaged Learning Activity
Watch the video entitled “Hyperkalemia in Primary Care Practice” by the National ...