Potassium & Magnesium Imbalance Conditions PDF

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, spina...

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  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  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+]