Diuretics: Uses, Types, and Mechanism

• Diuretics are "water pills" aiding the body in eliminating extra water and salt through urine.

Reasons for Use

• Lowering high blood pressure by reducing fluid volume, in turn, reducing pressure
• Alleviating swelling caused by fluid buildup, such as in ankles or lungs

Mechanism of Action

• Kidneys regulate the amount of water in the body.
• Diuretics prompt the kidneys to release salt (sodium), followed by water, into the urine
• Less water in the blood helps to lower blood pressure and reduce swelling

Thiazide Diuretics

• Hydrochlorothiazide is an example of a Thiazide diuretic
• Works at the far end of the kidney's filtering tube (distal tubule)
• Prevents the kidneys from reabsorbing salt and water during filtration
• Promotes the excretion of sodium and water while retaining calcium
• Mild water loss helps to lower blood pressure
• Can elevate blood sugar and uric acid levels that may worsen diabetes or cause gout
• Side effects include dizziness, sun sensitivity, and low potassium

Nursing/Patient Tips for Thiazide Diuretics

• Take in the morning to avoid nighttime urination
• Consume potassium-rich foods, such as bananas, unless medically contraindicated
• Monitor electrolyte levels and blood sugar

How to think if it

• Thiazide diuretics gently shut a valve that normally lets salt back into the body, so the salt and water get flushed out instead

Loop Diuretics

• Furosemide (Lasix) is an example of a loop diuretic
• Functions in the middle of the kidney's loop (loop of Henle), where significant salt reabsorption occurs
• Prevents the reabsorption of salt, potassium, and chloride
• Results in rapid and substantial water and salt excretion through urine
• Causes considerable fluid loss and is effective for heart failure, lung swelling, or kidney issues
• Also facilitates the removal of calcium and magnesium
• Side effects include hearing loss at high doses, low potassium, low calcium, low magnesium, dehydration, and dizziness when standing

Nursing/Patient Tips for Loop Diuretics

• Closely monitor electrolyte levels, especially potassium
• Track daily weight, with 2 lbs/day indicating fluid buildup
• Administered intravenously (IV) or orally based on the urgency of the condition

How to think if it

• Loop Diuretics works by opening a fire hydrant in your kidneys—the water pours out fast!

Potassium-Sparing Diuretics

• Spironolactone is an example of a potassium-sparing diuretic
• Acts at the end of the kidney tube (collecting duct)
• Blocks aldosterone, a hormone that encourages salt retention and potassium excretion
• Promotes the excretion of salt and water while preserving potassium levels
• Leads to gentle water loss
• Preserves potassium, which is beneficial when other diuretics cause excessive potassium loss
• The main side effect is elevated potassium levels

Nursing/Patient Tips for Potassium-Sparing Diuretics

• Avoid excessive consumption of potassium-rich foods if potassium levels are already elevated
• Monitor potassium levels regularly
• These diuretics have a slow action and are not very potent on their own

How to think if it

• Potassium-sparing diuretics turn off the body's “save salt” switch—so salt and water go out, but potassium stays.

Nursing Assessments and Patient Education

• Before administering diuretics, check blood pressure, weight, urine output, and lab results (particularly potassium levels)
• While on diuretics, daily weight monitoring is crucial to detect fluid buildup
• Watch for symptoms of low potassium, for example, leg cramps, irregular heartbeat
• Watch for symptoms of high potassium (with spironolactone), for example, fatigue, muscle weakness, and heart problems
• Monitor for dizziness upon standing, which indicates a risk of falling
• Take diuretics in the morning to avoid nighttime urination
• Change positions slowly to prevent dizziness
• Keep a log of daily weight and blood pressure
• Watch for muscle cramps, weakness, or irregular heartbeats
• Use sunscreen, as some diuretics increase sun sensitivity
• Report signs of dehydration, such as dry mouth, dizziness, and reduced urination

Diuretic Comparison

• Thiazide diuretics have mild strength, lose potassium, and are used for high blood pressure and mild swelling
• Loop diuretics have very strong strength, lose potassium, and are used for heart failure and big fluid issues
• Potassium-sparing diuretics have weak strength, keep potassium, and are often used with others