high urine osm?

[neoserenity333]

UW says that a urine osm of 360 is "high" - characterizing an SIADH patient.
I know the range is 50 - 1400, but does anyone know what "high" is? seems to me that SIADH would be higher than just 360.

thanks

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[Instatewaiter]

anytime the osm is over 300 you have concentrated urine relative to serum provided the serum osm hasnt changed too much.

 

[agranulocytosis]

I vaguely remember that question...if you actually work out the calculation of plasma osmolarity (I forget the equation but it's in chapter 4 of RR Path, something like 2*[Na] + 18/Glucose + something else), the plasma osmolarity was actually lower than urine osmolarity, and in that context, the urine osmolarity is excessively high. It's all relative to what the plasma osmolarity is.

 

[GynGuy1983]

anytime the osm is over 300 you have concentrated urine relative to serum provided the serum osm hasnt changed too much.

+1

That's usually the cutoff between the cortex and the medulla in the kidney. Look at the diagram in FA and it will clearly differentiate the two. You'll see that the more concentrated urine falls below the 300 mOsm cutoff in the outer medulla.

 

[DwyaneWade]

i Vaguely Remember That Question...if You Actually Work Out The Calculation Of Plasma Osmolarity (i Forget The Equation But It's In Chapter 4 Of Rr Path, Something Like 2*[na] + 18/glucose + Something Else), The Plasma Osmolarity Was Actually Lower Than Urine Osmolarity, And In That Context, The Urine Osmolarity Is Excessively High. It's All Relative To What The Plasma Osmolarity Is.

+1

🙂

EDIT: What happened???

 

[osli]

How in the heck does the quote function manage to change the case of every first letter?!? Or did you do something else strange? 😕

 

[DwyaneWade]

How in the heck does the quote function manage to change the case of every first letter?!? Or did you do something else strange? 😕

I have no idea.

How is your Saturday night going osli?

 

[neoserenity333]

y'all are awesome, thanks.

 

[Instatewaiter]

i Vaguely Remember That Question...if You Actually Work Out The Calculation Of Plasma Osmolarity (i Forget The Equation But It's In Chapter 4 Of Rr Path, Something Like 2*[na] + 18/glucose + Something Else), The Plasma Osmolarity Was Actually Lower Than Urine Osmolarity, And In That Context, The Urine Osmolarity Is Excessively High. It's All Relative To What The Plasma Osmolarity Is.

If you are talking about serum osm it is

2Na+ gluc/18 + Bun/2.8

 

[The Angriest Bird]

The question is, if you have SIADH, your urine osm should be WAY ABOVE 360.