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Discussion

Can my Professor be wrong?

Im a 1st year Nursing Student at Chamberlain College and im currently in Med Surg 1. We are discussing Fluids and Electrolytes. In lecture My Professor stated that an increase in osmolality leads to hypokalemia and from what ive studied its the exact opposite. From my understanding i thought an increase in osmolality would ultimately cause hyperkalemia. I didnt debate my Professor i just went home and tried to understanding her rationale. After reviewing the chapter again i still didnt get it. I emailed my professor this:

Good morning Professor,

This concept is concerning me. In class you stated that an Acute increased osmolality would cause Hypokalemia and that osmoles were essentially sodium. After reviewing the book again I found that osmolality is the concentration of molecules per weight, and in this case we are referencing blood serum or plasma which is ECF. If we know that the primary cation in the ICF is Potassium and the major cation in the ECF is Sodium and an excess of sodium in the ECF would cause a hypertonic environment, wouldn't that pull fluid from the cell which would contain potassium and ultimately cause Hyperkalemia? This really through me off in class and I cant seem to get passed it. Can you give me a rationale on why you stated an increase in osmolality would cause hypokalemia?

She responded:

Good morning

As I discussed, an episode of acute increase in osmolality can enhance the movement of potassium inside the cell.

Can someone help me understand how an increase in osmolality can cause hypokalemia moving potassium into the cell????

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    • Featured Replies

    I can't speculate as to what your professor considers "acute", but the increased osms from, say, DKA or HHS generally results in hyponatremia due to cellular shifts and hypokalemia due to massive diuresis.

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    Buddy,

    POTASSIUM STAYS WITHIN THE CELLS

    (as long as they are whole),

    so, if you throw something to increase your osmolarity in plasma (it can be sodium, glucose or something else - that is not principally important), the water will move from cells to there all right. But this water WILL NOT bring any potassium, because POTASSIUM STAYS IN THE CELLS.

    The result will be "dilution" of your hyperosmotic plasma and DECREASING concentration of potassium, - i. e. HYPOKALIEMIA.

    Try to make a picture if it is still not clear.

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    I can't speculate as to what your professor considers "acute", but the increased osms from, say, DKA or HHS generally results in hyponatremia due to cellular shifts and hypokalemia due to massive diuresis.

    BTW, when you treat your DKA and such, your patient gets low potassium not as much because of duress as by the mechanism I described, and also because by giving insulin you push more of it into cells. This is why the most dangerous time for arrhythmias for diabetics starts within an hour or so after insulin drip gets on.

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    • Author

    Now this makes sense to me. Thanks! The confusion was her statement when she responded in her email:

    "As I discussed, an episode of acute increase in osmolality can enhance the movement of potassium inside the cell"

    I couldnt understand why pottasium would be shifting inside the cell when its an intracellular cation unless insulin was involved...

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    • Author

    My rationale for increase osmolality leading to hyperkalemia is that a hyper osmotic ECF could result in hyperkalemia due to cell shrinkage and ultimately lysis causing pottasium to be released into the ECF..

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    The chemistry has been well addressed, so I'll just answer your question.

    Yes.

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    When you're talking about hypo or hyperkalemia you're talking about the plasma levels of potassium. Not what's in the cells. What's in the plasma surrounding the cells.

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    • Experts

    thread moved for best response

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    Her professor stated potassium goes inside the cell. So is she wrong or not?

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    This explanation was flawless...

    I'm not even in nursing classes yet, but I understood this.

    Kudos!

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