Does any fluid shift occur b/w ICF & ECF in hyper/hypo proteinemia?

[sylhet]

1. Plasma proteins are osmotically active substances and it determines the effective osmolarity between plasma and interstitial fluid. So, why dont we count plasma proteins to measure plasma osmolarity?

2. We know, if ECF osmolarity goes high, cells shrink and if ECF osmolarity goes down, cells swell up. Will there be any shift of water between ICF & ECF if theres hyperproteinemia & hypoproteinemia? If no could u pls explain why na and if yes why so?

PS. I was reviewing osmolarity and shifting of fluids b/w body fluid compartments. And this came up in my mind beacuse it is written in book that plsma protein is an osmotically active substance but i see no example of clinical conditions with plasma protein and shifting of fluids b/w ICF & ECF.

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[mfrizzo3]

Liver disease

 

[dukejen04]

When you lose a ton of albumin/protein in nephrotic syndrome you get all edematous.

 

[sylhet]

When you lose a ton of albumin/protein in nephrotic syndrome you get all edematous.

thank you but that fluid shift is in between plasma and interstitial fliud, right? we know when oncotic pressure goes down it favors filtration and this is the mechanism in case of nephrotic syndrome.

but do proteins loss realy cause water shift from INTRACELLULAR compartment?

i have an explanation i mean i have not found it in books. so please do correct me if I am wrong. As protein conc, goes down, oncotic pressure goes down so, fluid shift occurs from vascular compartment to interstitial fluid. Plasma osmolarity raises and at steady state both plasma and interstiatal compartments has same osmolarity and isotonic. And since ECF osmolarity remains unchanged, no fluid shift ocurs b/w ECF and ICF.

 

[Dr McSexy]

I'll take a stab, though I will wait for one of the smarter people to come and correct me

1. Plasma proteins are osmotically active substances and it determines the effective osmolarity between plasma and interstitial fluid. So, why dont we count plasma proteins to measure plasma osmolarity?

I think it has to with the fact that osmalilty and osmolarity are measured in respect the number of osmoles present in solvent/solution, where one molecule of sodium contributes the same as one molecule of albumin. Quantitatively speaking, sodium, glucose, urea (and a handful of other cations) make up 95% of the osmolality in plasma, where as albumin and other proteins make up a much less percentage of the osmolality, and thus are basically negligible as far as including them in the rough calculation for serum osmolality.

So, while change in protein the intravascular compartment has significant effects on fluid movement between interstitial and intravascular, it on the whole contributes little the osmolality of the serum.

 

[Dr McSexy]

Again, somebody correct me if I'm wrong...

2. We know, if ECF osmolarity goes high, cells shrink and if ECF osmolarity goes down, cells swell up. Will there be any shift of water between ICF & ECF if theres hyperproteinemia & hypoproteinemia? If no could u pls explain why na and if yes why so?
[/B]

but do proteins loss realy cause water shift from INTRACELLULAR compartment?

The loss of proteins doesn't directly cause shift in the compartments... however...

the loss of proteins causes a shift from intravascular to interstitial compartments (the shift is determined by starling forces). The shift causes a decreased effective circulating volume. In an attempt to correct this, the body activates the RAS and releases ADH. This results in the kidney reabsorbing a hypotonic solution of sodium that ultimately causes a decrease in the serum osmolality.

Now this is where you have an effect on the ICF and ECF compartments. This solution redestributes and you end up with an increase in volume in both the ICF and ECF compartments.

 

[piracetam]

Losing protein or not even producing them(nephrotics or kwashiorkor syndrome respectively) make you edematous. Ergo, losing protein impairs the osmolarity of the ECF. Albumin is responsible for oncotic pressure, along with other plasma protein. not having them shifts the water to ICF and interstitial space, making the edema.
cirrhotic, nephrotic and CHF(CHF causes pulmonary edema)