CKD, proteinuria, and waste products in the blood

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Why do patients with failing kidneys have so much Phosphorus, K, Na, BUN, etc, in the blood and yet have low blood protein levels, d/t the albumin being lost to the urine. My understanding is that damaged filtration leads to albumin being lost to the urine, so the question is if these holes in the filter allow for albumin to sneak through, why isn't K, Na, Ph, et al, also being lost to the urine? Instead most waste products are retained and concentrated in the blood (leading to high BP), except albumin, which is lost to the urine. CKD patients have hypoalbuminemia, right?, and their urine specific gravity is lower than normal, right? because their urine is not concentrating solutes.

I'm confused and this is bugging me. Someone help me straighten out this madness. I'm reading an old ATI book and it's not clarifying any of this.

Thanks.

BR

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Quick question: Are you a student?

The questions you ask are interdependent on the multitude specific disease processes affecting the renal system, and the physiology of glomerular filtration itself--all subjects in and of themselves.

You need to understand healthy kidney function first, including anatomy, factors influencing hydrostatic and osmotic pressures and how they affect filtration, molecular and ion sizes and basics of tubular reabsorption, to start.

Albumin is a plasma protein, and due to its size is easily lost to urine if the glomerular membrane and capillary walls is compromised, either by varied disease processes, or even bacterial toxins.

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Thank you Guttercat. I appreciate your response. I am a new RN. This was something I was pondering as I studied for the NCLEX.

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Specializes in Dialysis.

I would recommend reading this http://dl.dropboxusercontent.com/u/22400903/Books/The%20whole%20enchilada.pdf

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