Measuring Ions and Fluid Compartments

by Thad Wilson, PhD

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    Now we are going to take a look at how you measure the ions and fluid compartments. In the US, we oftentimes use something like a basic metabolic panel or what we term a Chem-7. This involves 7 different substances: sodium, potassium, chloride, bicarb, glucose, blood, urea, nitrogen, and creatinine. If you want to get a little bit more expanded panel, you can get other things like calcium, the total protein concentration albumin. These are all very important aspects to get a good feel for the ions, the osmolality potential, as well as the osmotic potential. If you want to measure osmolality directly, you have to put it into a machine. We do that with either freeze point depression or vapor depression. If you don't have those available and only have the Chem-7, you can calculate it. And this calculation is just done by this formula: you take 2 times the sodium concentration, glucose divided by 18 and the blood, urea, nitrogen divided by 2.8. So I provided you just an example here at the bottom. These are very typical sodium values of 140, glucose value of 80 mgs/dL, and a BUN of 8 mg/dL. If you go through the formula, it comes out to be 287 milliosmoles. And this is a very typical blood value. So the interstitium and the blood will be right around this 285-287. The intercellular component is just a teeny bit higher, maybe around 300 milliosmoles. So this is what is going to be circulating around in the body in comparison now to what is within a cell. We don't really know what cell osmolality is on a minute-to-minute basis because we don't really puncture the cell to measure its fluid concentration. We only measure what's in the blood. And that is why, measuring blood...

    About the Lecture

    The lecture Measuring Ions and Fluid Compartments by Thad Wilson, PhD is from the course Renal Physiology.

    Included Quiz Questions

    1. Sodium
    2. Glucose
    3. Blood urine nitrogen
    4. Albumin
    1. Creatinine
    2. ALP
    3. ALT
    4. Bilirubin
    5. Albumin
    1. Albumin
    2. Alpha globulin
    3. Beta globulin
    4. Glucose
    5. Sodium ions

    Author of lecture Measuring Ions and Fluid Compartments

     Thad Wilson, PhD

    Thad Wilson, PhD

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