What is the Difference Between Loop Diuretics and Thiazide Diuretics

Diuretics are medicines designed to clear extra fluid out and bring down blood pressure. They are particularly useful in conditions such as heart failure or other medical issues where fluid retention occurs. Diuretics are also known as water pills due to their ability to reduce the fluid buildup in the body. Most diuretics help the kidneys to remove salt and water through the urine flow. Loop diuretics and thiazide diuretics are two different types of diuretics used for the management of hypertension.

The key difference between loop diuretics and thiazide diuretics is their mechanism of action. Loop diuretics act on the thick ascending limb of the loop of Henle in the kidneys, whereas thiazide diuretics target the distal convoluted tubules in the kidneys.

CONTENTS

1. Overview and Key Difference
2. What are Loop Diuretics  
3. What are Thiazide Diuretics
4. Similarities – Loop Diuretics and Thiazide Diuretics
5. Loop Diuretics vs Thiazide Diuretics in Tabular Form
6. Summary – Loop Diuretics vs Thiazide Diuretics
7. FAQ – Loop Diuretics and Thiazide Diuretics

What are Loop Diuretics?

Loop diuretics are a type of diuretics that act on the Na-K-Cl cotransporter along the thick ascending limb of the loop of Henle in the nephrons of kidneys.  Loop diuretics are usually more effective in patients with impaired kidney function. They act on the Na⁺-K⁺-2Cl⁻ symporter (NKCC₂) in the thick ascending limb of the loop of Henle in order to inhibit sodium, chloride, and potassium reabsorption, ultimately resulting in increased urine production.

Loop diuretics are used in medicine to treat hypertension and edema, which is usually due to congestive heart failure or chronic kidney disease. Furthermore, the most commonly used loop diuretics are furosemide, bumetanide, and torsemide. The common side effects of loop diuretics may include dizziness, headache, gastrointestinal upset, hyponatremia, hypokalemia, and dehydration.

What are Thiazide Diuretics?

Thiazide diuretics are a type of medication used to control hypertension, partly by inhibiting the reabsorption of sodium (Na+) and chloride (Cl−) ions from the distal convoluted tubules in the nephrons of the kidneys. They achieve this by blocking the thiazide-sensitive Na+-Cl− symporter. Moreover, thiazide diuretics are more effective in patients with normal kidney function.

Examples of thiazide diuretics include indapamide, bendroflumethiazide, chlortalidone, cyclopenthiazide, and xipamide. Additionally, common side effects of thiazide diuretics may include a possible increase in blood sugar levels, a potential increase in the level of uric acid, low blood levels of potassium, sodium, and magnesium, high levels of calcium, upset stomach, dizziness upon standing, erectile problems, and increased skin sensitivity to sunlight.

Similarities Between Loop Diuretics and Thiazide Diuretics

1. Loop diuretics and thiazide diuretics are two different types of diuretics used for the management of hypertension.
2. Both are also known as water pills.
3. Both act on different symporters of the nephron of the kidney.
4. They can cause side effects.

Difference Between Loop Diuretics and Thiazide Diuretics

Definition

1. Loop diuretics are a type of diuretics that is usually more effective in patients with impaired kidney function.
2. Thiazide diuretics are a type of diuretics that is usually more effective in patients with normal kidney function.

Mechanism of Action

1. Loop diuretics act on the Na+-K+-2Cl− symporter (NKCC2) in the thick ascending limb of the loop of Henle in order to inhibit sodium, chloride, and potassium reabsorption, ultimately resulting in increased urine production.
2. Thiazide diuretics inhibit the reabsorption of sodium (Na+) and chloride (Cl−) ions from the distal convoluted tubules in nephrons of the kidneys by blocking the thiazide-sensitive Na+-Cl− symporter, resulting in increased urine production.

Uses

1. Loop diuretics are used to treat hypertension and edema, which are usually due to congestive heart failure or chronic kidney disease.
2. Thiazide diuretics are used to control hypertension.

Examples

1. Furosemide, bumetanide and torsemide are examples of loop diuretics
2. Indapamide, bendroflumethiazide, chlortalidone, cyclopenthiazide and xipamide are examples of thiazide diuretics.

Side Effects

1. Loop diuretics may cause dizziness, headache, gastrointestinal upset, hyponatremia, hypokalemia, and dehydration.
2. Thiazide diuretics may cause an increase in the blood sugar level, a possible increase in the level of uric acid, a low blood level of potassium, sodium, and magnesium, and a high level of calcium, upset stomach, dizziness on standing, erection problems and skin sensitivity to sunlight.

The infographic below presents the differences between loop diuretics and thiazide diuretics in tabular form for side-by-side comparison.

Summary – Loop Diuretics vs Thiazide Diuretics

Diuretics or water pills help to reduce the fluid buildup in the body. Loop diuretics and thiazide diuretics are two different types of diuretics. Loop diuretics are a type of diuretics that are usually more effective in patients with impaired kidney function, while thiazide diuretics are a type of diuretics usually more effective in patients with normal kidney function. Furthermore, loop diuretics act on the thick ascending limb of the loop of Henle in the kidneys, whereas thiazide diuretics act on the distal convoluted tubules in the kidneys. Thus, this summarizes the difference between loop diuretics and thiazide diuretics.

FAQ: Loop Diuretics and Thiazide Diuretics

1. What are loop diuretic drugs?

• The main examples of loop diuretic drugs are bumetanide (Bumex), ethacrynic acid (Edecrin), furosemide (Lasix), and torsemide (Sooanz).

2. What is the mechanism of loop diuretics?

• Loop diuretics act on the Na+-K+-2Cl− symporter (NKCC2) in the thick ascending limb of the loop of Henle to inhibit sodium, chloride, and potassium reabsorption, ultimately resulting in increased urine production.

3. What are the examples of drugs used as thiazide diuretics?

• Examples of thiazide diuretics include chlorothiazide, chlorthalidone, hydrochlorothiazide, indapamide, and metolazone.

4. What is the mechanism of thiazide diuretics?

• Thiazides achieve their diuretic action by inhibiting the reabsorption of sodium (Na+) and chloride (Cl−) ions from the distal convoluted tubules in nephrons of the kidneys, blocking the thiazide-sensitive Na+-Cl− symporter and resulting in increased urine production.

5. What are the major side effects of thiazide diuretics?

• The major adverse effects of using thiazides may include hypokalemia, hyponatremia, metabolic alkalosis, hypercalcemia, hyperglycemia, hyperuricemia, hyperlipidemia, and sulfonamide allergy.

Reference:

1. “Loop Diuretic.” ScienceDirect Topics.
2. Dr Rachel Hudson, MRCGP. “Thiazide Diuretics: Uses and Side-Effects.” Patient.Info.

Image Courtesy:

1. “Loop diuretics” By NEUROtiker – Own work (Public Domain) via Commons Wikimedia

2. “Hydrochlorothiazide costs (DrugStats)” By ClinCalc DrugStats (CC BY-SA 4.0) via Wikimedia Commons