Lab Values, part 24: Albumin, Prealbumin, & Total Protein

Hi, I'm Meris, and in this video, I'm going to be talking to you about the lab values prealbumin, albumin, and total protein. Let's go ahead and get started.

All right. So first up, let's talk about albumin. What is it? It's a protein that's made by the liver and is really, really important. It is used in transporting substances throughout my body. It's a carrier protein, but it's also used to synthesize other proteins. So this is a very, very important one. And albumin is able to most accurately reflect a patient's long-term nutritional status. So we're not talking about the short-term, the immediate period, but we're talking about kind of historically, in the past couple of weeks to months, what has this patient's nutritional status been like. The other thing about albumin is that, remember, protein is really important when it comes to maintaining our fluid balance. Protein acts like a water magnet. So it's really, really important that there's the right amount of albumin so that we don't end up losing fluid because we don't have anything to hold on to it and to affect that diffusion. So really, really important, protein, for a lot of our various biochemical activities day-to-day, okay? So this is not just-- it doesn't have just one job. It's a super, duper important molecule. And when we don't have it, bad things happen. So the expected range here - I always love this because it's very similar to one of our others - is 3.5 to 5 grams per deciliter. So 3.5 to 5. And the way that we can help you remember this is with our cool chicken hint here, which is that Al is always bumming like 3 to 5 dollars off of me. My friend Al, he is always trying to get a couple of bucks for me. 3 to 5 bucks. That's all he ever asks me for, right? So that's how you can help remember that albumin is 3 to 5 because Al is always bumming, right? 3.5 to 5.

Now, what if I have decreased levels of albumin in my blood? Well, here's some possible causes. Liver disease. If it's a protein that's produced by the liver, then liver disease is a possible cause of a decrease in it. Kidney disease. Now, this one I want to just call your attention to here. The kidney disease doesn't have anything to do with the fact that it's producing albumin. What is happening here is that if you have something like nephrotic syndrome or acute glomerulonephritis or something like that, where your kidneys are now, they are much leakier. They're letting these bigger molecules through, right? And when that happens, you're losing it. So you're going to lose it from the body because of how it is being excreted in the urine. So just a little clinical pearl for you here. If you see somebody who has really, really frothy urine, I want you to keep in mind that could be due to proteinuria. They could be passing large amounts of protein in their urine. And if that's the case, they may be in a state of hypoproteinemia. They have decreased protein in their blood.

So what happens though, and this is the point of this, is that when I have these low levels, I'm going to end up with that fluid balance problem, right? I'm going to end up with my fluid not being where I want it to be. So you will see that patients with low albumin, they can have edema and fatigue and weakness. And this kind of goes hand in hand with another cause, which is malnutrition. I just want you to remember that if I'm not taking in enough protein to be synthesized into other proteins, then I'm not going to be able to do things like make albumin. So malnutrition is also possible here as well. So just think about your patient who is really lethargic, they're weak, and they may be edematous, too, related to that lack of protein and the inability to draw water back into the vascular space. That's the point of albumin too, is that it's going to help provide that oncotic pressure to bring fluid back from the interstitial space into the vascular space so that we can maintain our blood pressure and our fluid volume, okay?

Now, we've talked about albumin. I want to shift gears slightly and talk about prealbumin. Now, prealbumin, this is also a protein that's made by the liver, and it does many of the same things. It's important in the transport of different substances and the synthesis of other proteins. But prealbumin is going to most accurately reflect my patient's current or recent nutritional status. So this is a great lab for helping us say like, "What's going on right now with this patient?" We're not talking necessarily about long-term malnourishment, but is this a patient who is experiencing some recent starvation? Or is this a patient with food insecurity who is not able to meet their protein needs, or whatever the situation may be? The expected range here is going to be 15 to 36 milligrams per deciliter. Again, we expect you to have prealbumin floating around, so we don't want it to be close to 0 in this case. But when we talk about decreased prealbumin, we're looking at less than 15. This in particular is related to protein-calorie malnutrition. Now, remember I told you that with albumin, malnutrition is a possible cause of a decreased level, but there's other stuff too, such as liver and kidney dysfunction. But with prealbumin, what we are talking about right here is if that is low, that is related to protein-calorie malnutrition. That is related to a poor intake of proteins and calories by my patient.

So why is this important? Why do you care? Well, first of all, you need to know the difference between the two on where to look for which problems. But second of all, prealbumin is going to be one of these labs that's really important when we're talking about somebody who's having a change to their nutrition. And when we are talking about somebody who's having a change to their nutrition in the acute care setting, my mind goes right away to somebody who's going to be on TPN, total parenteral nutrition. This is a person who is not being able to be fed through the GI tract. This is somebody who's receiving all the total of their nutrition through the parenteral route, meaning going around the GI tract, such as through a central line, okay? This patient, we have to make sure that we are meeting their caloric needs and their protein needs. Yes, we're going to check their sugar because we need to make sure they're meeting their carbohydrate needs too, but we're also going to monitor that prealbumin to see how their nutritional status is while they are on TPN. So that is the thing that you need to know, is that prealbumin is the lab value of choice for measuring the effectiveness of TPN.

All right. Let's switch gears slightly, and we'll round this video out by talking about total protein. So total protein is the amount of albumin and globulin found in the fluid portion of the blood, okay? So here, we are just looking at those big proteins, albumin and globulin, that live in the plasma all the time. We add those together, and that gives us our total protein. And we expect that range to be 6.4 to 8.3 grams per deciliter, okay? Now, what are some possible causes of a decreased total protein? Well, again, liver disorders related to that albumin, malnutrition related to poor protein or calorie intake, kidney dysfunction related to the loss of proteins through excretion, celiac disease, again, related to malnutrition, to that inflammatory process limiting how much can be absorbed, and then inflammatory bowel disease. Anything where we are talking about inflammation in the bowels, we are also talking about the potential for malnourishment. So that is on the menu for us as well.

All right. I'm so glad you stayed until the end because I'm going to test your knowledge of some key facts I provided in this video with some quiz questions.

Albumin is considered a more sensitive marker than prealbumin for assessing which aspects of a patient's nutritional status?

Their long-term nutritional status.

Which lab value should the nurse monitor in a patient receiving total parenteral nutrition?

Prealbumin.

All right. That is it for this video. I do hope you learned something. I'll see you in the next one. Thanks so much, and happy studying.