Pharm 343.03 Conditions of K & Mg Imbalance-HO PDF

Conditions of Potassium & Magnesium Imbalance Scot H. Simpson, BSP, PharmD, MSc Professor Pronouns: He, Him...

Conditions of Potassium & Magnesium Imbalance Scot H. Simpson, BSP, PharmD, MSc Professor Pronouns: He, Him ©2024, Scot H. Simpson Copyright-protected material contained herein is reproduced either with permission from the rights holder or under the terms of the Copyright Act. This material is being made available for your individual use; other use of this material has not been authorized and may require permission of the rights holder.  Lecture Objectives / Outline Potassium imbalances Magnesium imbalances – Hypokalemia - Hypomagnesemia – Hyperkalemia - Hypermagnesemia Describe the signs and symptoms of electrolyte abnormalities Describe management strategies for electrolyte abnormalities Associated Readings (Pharmacotherapy 12th ed): – Chapter 70 (Disorders of Potassium and Magnesium Homeostasis) 2  Potassium (K+) Daily potassium intake 4700 mg (Adequate Intake) – Most Canadians do not reach this recommendation – Foods with a high potassium content*: fruits (apricots, bananas, guava, kiwifruit, nectarines), vegetables (broccoli, spinach), potatoes, milk, yogurt, bran cereals Potassium is the most abundant intracellular cation – 98% of total body potassium is located within cells Actively transported into cells – Via the Na+-K+-ATPase pump Major determinant of the resting action potential – Neurons – Skeletal muscle cells – Cardiac myocytes 3 *Source: Table 70-2. Pharmacotherapy: A Pathophysiologic approach, 12th ed.  Potassium Concentration Normal serum potassium concentration (represents about 2% of total body K+) – 3.5-5.0 mmol/L (mEq/L) Serum potassium concentration is affected by – Dietary intake – Excretion from the kidneys (90%) and gastrointestinal system (10%) – Sequestration in muscle and hepatic cells – Hormone levels (insulin, aldosterone) – Acid/Base balance Gumz ML, et al. N Engl J Med 2015;373(1):60-72. 4  Lecture Objectives / Outline Potassium imbalances Magnesium imbalances – Hypokalemia - Hypomagnesemia – Hyperkalemia - Hypermagnesemia Describe the signs and symptoms of electrolyte abnormalities Describe management strategies for electrolyte abnormalities Associated Readings (Pharmacotherapy 12th ed): – Chapter 70 (Disorders of Potassium and Magnesium Homeostasis) 5  Hypokalemia Symptoms Hypokalemia occurs when serum potassium 6 mmol/L Loss of P wave Widening of QRS complex QRS complex & T wave 17 merge, creating a Sine-wave Source: Figure 70-1. Pharmacotherapy: A Pathophysiologic approach, 12th ed.  Hyperkalemia Causes Increased potassium intake – Over correction of hypokalemia Decreased potassium excretion – Acute or chronic renal failure – Adrenal insufficiency Redistribution of potassium into extracellular space – Metabolic acidosis 18  Drug-Induced Hyperkalemia Angiotensin Converting Enzyme (ACE) inhibitors Angiotensin Receptor Blockers (ARBs) Direct renin inhibitors Mineralocorticoid Receptor Antagonists (MRAs) Potassium-sparing diuretics Nonsteroidal anti-inflammatory drugs (NSAIDs) 𝛽-blockers Digoxin Cyclosporine Tracolimus Trimethoprim/Sulfamethoxazole 19  Lecture Objectives / Outline Potassium imbalances Magnesium imbalances – Hypokalemia - Hypomagnesemia – Hyperkalemia - Hypermagnesemia Describe the signs and symptoms of electrolyte abnormalities Describe management strategies for electrolyte abnormalities Associated Readings (Pharmacotherapy 12th ed): – Chapter 70 (Disorders of Potassium and Magnesium Homeostasis) 20  General Considerations Evaluate severity of hyperkalemia, rate of onset, and patient’s clinical condition Identify any diet or drug-related contributions to elevated potassium levels Goals of therapy: – Minimize cardiac conduction effects Administer intravenous calcium to raise the cardiac threshold potential (antagonizes cardiac membrane effect of hyperkalemia) – Return serum and total-body stores of potassium to normal levels 21 Management of Mild to Moderate Hyperkalemia Asymptomatic patients with [K+]