Diuretics Flashcards
How much blood do the kidneys filter every minute?
About a half cup
Why do the kidneys filter the blood?
To remove wastes and extra water to create urine
What structure allows urine to flow from the kidneys to the bladder?
The ureters
What makes up the urinary tract?
The kidneys, ureters, and bladder.
What is tubular reabsorption?
The process by which the nephron removes water and solutes from the tubular fluid and returns them to the circulating blood.
What is tubular fluid?
Pre-urine
What is glomerular filtration rate (GFR)?
The rate at which the glomeruli filter the blood.
What is a normal glomerular filtration rate?
120 ml water/minute
How do we measure the glomerular filtration rate?
By measuring the creatinine clearance.
What is clearance?
The complete removal of a substance from the blood.
What is a diuretic?
A drug that increases the formation of urine in the body by changing the rate of excretion of specific electrolytes such as sodium and potassium.
Why might you need a diuretic?
- edema due to congestive heart failure
- acute pulmonary edema
- liver disease (cirrhosis)
- renal disease
- hypertension
- conditions that cause hyperkalemia
What is renal failure?
A decrease in the kidney’s ability to filter the blood to remove metabolic wastes. Can be acute or chronic.
What percentage of nephrons need to be functional to maintain normal renal function.
50%
What is the best marker for estimating kidney function?
Glomerular filtration rate
What can acute renal failure cause the blood to retain?
Nitrogenous wastes
What can cause acute renal failure?
Renal hypo-perfusion due to hypertension, dysrhythmias, heart failure, and shock.
What can cause chronic renal failure?
Long-standing hypertension and diabetes.
Is chronic renal failure reversible or irreversible?
Irreversible
What is ascites?
When fluid collects in the spaces in the abdomen.
How many different types of diuretics are there?
4
Where do osmotic diuretics act?
In the proximal tubule
How do osmotic diuretics work?
They pull water into the renal tubules from the surrounding tissues an inhibit tubular reabsorption of water and solutes, thus producing rapid diuresis.
Why might you need osmotic diuretics?
- increase glomerular filtration rate to help prevent kidney damage during acute renal failure
- reduce intracranial pressure or cerebral edema
- reduce intraocular pressure
- promote excretion of toxic substances
How much solute is excreted with osmotic diuretics?
65%
Name an osmotic diuretic:
Mannitol (Osmitrol)
How do loop diuretics work?
They prevent the reabsorption of sodium and chloride by blocking the sodium/potassium/chloride symporter in the loop of Henle.
Where do loop diuretics act?
In the loop of Henle
How much solute is excreted in loop diuretics?
20%
Name an example of a loop diuretic:
Lasix (Furosemide)
Should you take Lasix if you’re pregnant?
No
Should you take Lasix if you are allergic to sulfonamide antibiotics?
No
What are the adverse effects of Lasix?
Hypovolemia, orthostatic hypotension, syncope, nausea, vomiting, ototoxicity.
Should you take Digoxin at the same time as Lasix?
No
What does Lasix do to you if you’re also taking anti-hypertensives?
Increases hypotension even more
What does Lasix do Insulin?
It diminishes it’s effect
When should you contact your physician about weight gain while taking Lasix?
If the weight gain is greater than 3 lbs in one day.
What do potassium sparring diuretics do?
They increase urine output but promote the retention of K+
What does aldosterone do?
It promotes the reabsorption of sodium and secretion of K+
How do potassium diuretics work?
They are aldosterone antagonists so they prevent the reabsorption of water by preventing the reabsorption of Na+ but retain K+
Where do potassium sparring diuretics work?
The collecting duct
How much solute is excreted with potassium sparring diuretics?
5%
Name an example of a potassium sparing diuretic
Spironolactone
What are some of the side effects of spironolactone?
- amenorrhea
- irregular menses
- postmenopausal bleeding
- muscle weakness
- fatigue
- bradycardia
What type of drugs interact with Spironolactone
Antihypertensive drugs and potassium supplements
How do thiazide diuretics work?
They block sodium nd chloride reabsorption at the distal tubule, reducing the reabsorption of water.
Do thiazide diuretics promote ototoxicity?
No
Where do thiazide diuretics act?
In the distal tubule.
How much solute is excrete with thiazide diuretics?
10%
Name a thiazide diuretic:
Chlorothiazide
What drug interactions are there with chlorothiazide?
- antihypertensive drugs
- reduced effectiveness of coagulants, sulfonylureas, and antidiabetic drugs
What are some symptoms of hypokalemia?
Fatigue, general malaise, muscle twitching, and cardiac irregularities.
What foods are high in potassium?
Bananas, oranges, dates, apricots, raisins, broccoli, green beans, potatoes, meats, fish, and legumes.
