Step I Diuretics - Urine Osmolality

[DrTacoElf]

So let me get this straight in terms of URINE OSMOLALITY

Osmotic diuresis, like from DKA/mannitol is HYPOTONIC

Loop/Thiazide diuresis, like from furosemide is HYPERTONIC


Anything else to add?

 

[turkeyjerky]

well, sorta. osmotic diuretics cause a hypoosmotic loss of fluid from the patient, but the actual urine is isoosmotic. this is because you're adding osmoles to the blood that will be quickly filtered and excreted.

loop diuretics cause a loss of hypo or isoosmotic fluid. this is because they f/u the medullary concentrating power of the loop of henle. thiazide diuretics, uniquely, cause a loss of hypertonic fluid. this is because they act in the distal tubule after the medullary gradient has been established.

 

[DrTacoElf]

well, sorta. osmotic diuretics cause a hypoosmotic loss of fluid from the patient, but the actual urine is isoosmotic. this is because you're adding osmoles to the blood that will be quickly filtered and excreted.

loop diuretics cause a loss of hypo or isoosmotic fluid. this is because they f/u the medullary concentrating power of the loop of henle. thiazide diuretics, uniquely, cause a loss of hypertonic fluid. this is because they act in the distal tubule after the medullary gradient has been established.

so is it safe to assume that the urine is hypertonic when thiazides are used and hypo or isotonic when loops are used?

 

[turkeyjerky]

yeah, that's prolly safe to assume.