Diuretic Overview

There are a couple major medications to know related to the Renal System, but one of the main ones you need to understand are diuretics.

There are three types of diuretics:  Loop, thiazide, and potassium-sparing.  Furosemide (Lasix) is a Loop diuretic, which is usually the diuretic tried first, so it tends to be most common.  Make sure you know the effects of Loop diuretics on potassium!  If the patient is not careful, they can be at risk for hypokalemia.

Thiazide diuretics will usually be tried if the patient cannot take Loop diuretics for some reason, or if the Loop diuretics are not effective for that patient.  Thiazide diuretics work by preventing the kidneys from reabsorbing sodium, which means more sodium stays in the urine.  And since water (this time in the form of urine) always tries to follow sodium, then the body tends to lost water along with the sodium.

Potassium-sparing diuretics are also used when needed, with the most common example being spironolactone (Aldactone).  Since this type of diuretic is “potassium-sparing,” it has the opposite effect on potassium in the body than Loop diuretics do.  That means you need to watch your patient for signs of hyperkalemia.

Another diuretic sometimes used is mannitol (Osmitrol), which is a salt.  It works by inhibiting (stopping) water reabsorption in the kidneys.  Since the water has trouble getting reabsorbed back into the blood stream during filtration, then more water will end up leaving the body in the urine.

2 thoughts on “Diuretic Overview”

  1. Dana Lewis

    I always get mixed up on Na and K. I just remember that they are opposites of eachother. When one is high, the other is low. Just when I think I understand, I confuse myself. Is there a way to remember those especially when it comes to diuretics? Thanks

    1. With diuretics, I usually only think about K. Loop diuretics cause K to be low (it goes out with the urine). Potassium-sparing diuretics cause K to be high (it stays in the blood instead of going into the urine).

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