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Laboratory Values

by Jill Beavers-Kirby
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    00:01 Hi, my name is Jill Beavers-Kirby and today we are going to be talking about some lab values that you are going to find on your NCLEX exam. We are not going to talk about every single lab value, just the most common ones that are on the test.

    00:14 So the first one is the electrolytes. We are going to talk about potassium first.

    00:21 So potassium is the most common intracellular ion. You find potassium in every single cell. Normal potassium values are 3.5 to 5.0 mEq/L.

    00:33 Why do we need potassium? Well it keeps our muscles contracting the way they should, keeps our heart beating the way it should and it helps with nerve conduction. So what is hypokalemia? That is any potassium level that is less than 3.5 mEq/L. What causes hypokalemia? Well we lose a lot of electrolytes in our body fluids. So any time we have vomiting, nausea, diarrhea or if somebody is undergoing gastric suctioning. You usually see this when somebody has had surgery and they are hooked up to NG tube, which is the nasogastric tube, that goes down into their nose. And sometimes you have the suction of the extra bile and extra stomach fluids after surgery to help the patient feel better.

    01:23 You got to keep in the back your mind that you are suctioning out the electrolytes. So what are symptoms of low potassium? The same symptoms that are symptoms for pretty much everything else in medicine, nausea, vomiting and diarrhea. However with potassium you may also see an irregular heartbeat.

    01:40 You can feel this when you check somebody's radial pulse or if they're hooked up to a cardiac monitoring, you might see some little extra beats in there that don't belong. So how do we treat low potassium? Well if your patient is able to eat, you are going to tell them to eat high potassium foods. What are high potassium foods? Anything with the peel. So remember P for potassium, P for peel. So think of potatoes, they have a peel, bananas those have a peel, oranges those have a peel. Anything with the peel has high potassium.

    02:13 Or if your patient is unable to eat enough food to keep their potassium level up, you want to get them potassium supplements. Unfortunately most potassium supplements are pretty big pills and patients don't really like to take them.

    02:27 But you have to stress the importance of keeping their potassium levels normal because of the heart rate and nerve conduction issues.

    02:35 If your patient is unable to eat and keep their potassium levels up via foods or supplements, then you have to give them IV potassium. You can give that peripherally through a line in their arms. In that case you have to give it slow 10 mEq/hr or if they have a central line they can get the rates a little faster. But they have to be on a cardiac monitor to make sure they are not getting too much potassium too quick. On the other end of this potassium balance is high potassium. This is when your potassium is greater than 5 mEq/L.

    03:13 We usually see this in kidney failure patients because remember I said we lose potassium in our body fluids. So if you are a kidney failure patient and you are not able to urinate, your potassium is going to build up.

    03:27 Another time we see this is when your patient is taking too many of those potassium supplements. Those big horse pills that are hard to swallow.

    03:36 Sometimes patients really do take them like they are supposed to and their potassium levels are too high.

    03:41 Another thing that causes high potassium levels are burn or crush injuries.

    03:47 This comes from the trauma down to the muscle tissue where potassium is released from the muscles. It causes your potassium levels to become elevated. What are the symptoms? Well you are going to see EKG changes. Those are tall tented T waves on an EKG. If you have tall tented T waves on an EKG or on your heart monitor you want to get an EKG and assess the patient for a higher level of potassium. Really high potassium levels, say around 7 mEq/L cause muscle weakness, and confusion, and ventricular fibrillation which will eventually lead to cardiac arrest. So you have to be very diligent about monitoring your patient for elevated levels of potassium. So how do we fix high potassium? Well, one of the easiest ways is to tell the patient quit taking all the potassium supplements and to stop them before their potassium levels get too high. Or there is medicine called Kayexalate which causes diarrhea. Once again we are losing our body fluids. So this is how we get rid of our own potassium.

    04:54 Kayexalate looks like chocolate milk and it smells really syrupy sweet.

    05:00 Patients will usually take it because it is palatable and it will usually cause diarrhea in about 30 minutes. So this is going to help them get rid of their potassium. Another way to help them get rid of their potassium is with diuretics such as Lasix. Why? Because it's causing us to urinate and we are losing our potassium that way. If potassium levels are really, really high you have to put the patient on dialysis. If it's a kidney patient and filter out their potassium. You can also give IV sodium bicarbonate or calcium gluconate. What this does? Is it forces the potassium out of the body. The next electrolyte is sodium. Sodium is the major extracellular ion. So this is the major ion that is outside the cells.

    05:49 Normal is 135 to 145 mEq/L.

    05:54 And why do we need sodium? To maintain water balance.

    05:59 So if you think of sodium as salt, you eat too much salt, you intake too much sodium, you get swelling, you get water weight gain, you get ankle puffiness. All those are unfortunate side effects that none of us really like. What do we feel if our sodium level is too low? If the sodium level is less than 135 mEq/L, you'll notice that your patient is confused. What causes somebody's sodium levels to go too low? Those GI losses again, vomiting, gastric suctioning, too much diuretics.

    06:35 Some people who have heart failure will take a lot of diuretics which causes a lot urination, once again losing all those body fluids. If you have a significant burn, the patient lose these through their skin or if they have a large wound that is draining body fluids again.

    06:56 This can cause low sodium. So your confused little patient is going to come in and their mentation is going to be off. They might have some nausea, they might have some muscle spasms. When sodium level is getting really, really low, your patient has a risk for seizure. So how do we fix low sodium? Well we encourage sodium rich foods. I had a patient who loved water chestnuts wrapped in bacon and he would dip them in soy sauce.

    07:25 And this helps the sodium. All because those three foods are themselves high in salt.

    07:30 You also want to tell them to cut down on their water because they can dilute out the blood sodium. Some patients will drink way too much water and that causes all the electrolytes to look low. You can also give sodium via IV which is usually 0.9% sodium is the normal fluid or if their sodium is really, really low we give a hypertonic solution of 0.3% saline.

    07:55 You have to give this slow and replace the losses slowly.

    08:01 Just because the losses didn't occur all of a sudden. So we replace this losses gradually over time to allow the body to the equilibrate.

    08:12 So on the other side is hypernatremia. This is when your sodium level is greater than 145 mEq/L. This is usually seen in dehydration when patients aren't taking enough water or fluids or in a metabolic condition called diabetes insipidus. This is when your body can't concentrate the fluids.

    08:33 So even though you have a large amount of urine output it is not concentrated at all. So you're hanging onto your sodium. Or sometimes people just over salt everything and they just simply taken too much sodium intake. So what are the symptoms? Weakness, and confusion, I know sound familiar, these are the symptoms for everything. But you can look in their mouth and their mouth will be really dry. Their eyes will be really dry. Because they are dehydrated. Their skin turgor will be off because once again they are dehydrated. So you will notice the tenting of the skin will be longer than 3 seconds. And their blood pressure might be low because they are dehydrated. They just don't have enough fluids going through their system. So how do we treat this? We treat this with IV fluids such as dextrose or oral fluids just as plain water. And we also highly, highly, highly encourage the patient to quit using so much salt and salting their foods. So another electrolyte that's found in our body is calcium. And on lab test results, you might see two levels for calcium. You might see a total calcium and an ionized calcium. Ionized calcium is more specific to the calcium that's in the specific cells. Total calcium also takes into account the amount of calcium in the blood.

    09:53 Most physicians will use that ionized calcium levels to treat patients though.

    09:58 Why do we need calcium? This is needed for muscle contraction and blood clotting. So a normal ionized calcium is 4.5 to 5.2 mg/dL.

    10:10 Hypocalcemia is less than 4.5 of an ionized calcium. What causes this? Kidney failure, pancreatitis which is irritation and inflammation of your pancreas, diuretics such as Lasix, steroids such as high doses of prednisone and hyperparathyroidism. So your parathyroid gland is the gland that's along your thyroid and it also helps to regulate our calcium. So if your parathyroid gland is not functioning you can have an alteration in your level of calcium.

    10:48 So the symptoms of low calcium are pretty distinct. One of them is Trousseau's sign. This is when a patient has a blood pressure cuff on and as you're inflating the cuff, the hand will spasm like this where the middle finger comes into the palm. It's a pretty classic sign. The other sign of low calcium is called Chvostek's. Chovstek's sign is if you tap the person's cheek, their mouth will spasm in relation just to the tapping because you are irritating that nerve.

    11:28 So how do we treat low calcium? We give them calcium. You give calcium gluconate or you give calcium chloride. Calcium will be better absorbed if you can give it with orange juice. It's kind of a side note. So if you have low calcium, then you can also have high calcium.

    11:46 High calcium is seen when you have certain diseases such as cancer or with excess calcium intake.

    11:55 What are the symptoms? Nausea, vomiting, confusion, and an irregular heartbeat.

    12:00 High calcemia is harder to pick up on just because the symptoms are rather vague and those are the symptoms for pretty much everything else. But we treat this by giving the patients IV fluids such as normal saline to help kind of dilute that calcium amount, diuretics to help them rid their body of their body fluids, all that excess water, oral fluids if they are able to eat and drink enough to sustain. Or you can give a binding agent called Calcitonin. This is an IV medication.

    12:32 It binds to the extra calcium in the system, so that the calcium doesn't affect the other body parts.

    12:39 Another very important electrolyte is magnesium. Normal magnesium is 1.5 to 3 mEq/L.

    12:45 Magnesium is needed for muscle and nerve conduction, heartbeat, regulation of blood pressure and blood sugar. So remember magnesium, muscles when you think muscles, think of nerves because you have to have nerves to make your muscles move. So M for magnesium, M for muscles.

    13:05 Hypomagnesemia or low magnesium is defined as a magnesium level of less than 1.5 mEq/L. This is caused from inadequate absorption. So if you are eating and for whatever reason your gut just can't absorb the electrolytes or from diarrhea. Once again you are getting rid of body fluids and that's where all your electrolytes are. Alcoholism, because of poor nutrition or poorly controlled diabetes. Because high blood glucose is not allowing your body to absorb the magnesium. So what are the symptoms? You are going to see hyperactive reflexes, remember M for magnesium, M for muscles and the nerves innervate your muscles. So your muscles are going to be very over reflexic. You can also be confused. You can also have some tremors. And if the low magnesium level goes on long enough it can lead to seizures. So how do we treat low magnesium? If the patient is able to eat, we ask him to increase the intake of foods that are high in magnesium. This includes greens like kale, spinach.

    14:18 It also includes chocolates and nuts. So one of the best way to replace your magnesium is to eat chocolate covered nuts. Dark chocolate has more magnesium in it. So that is even better for the patient. You can also supplement magnesium with intravenous magnesium. You can give 2gms/hr via an IV even in a peripheral IV. Another way to supplement magnesium is with magnesium pills.

    14:47 However one of the biggest side effects of magnesium pills is diarrhea. So it is really hard to tell your patient to take magnesium pills which may cause diarrhea which may make you lose your magnesium but take more pills. So best thing to do if they are able to eat and drink have them try to increase their foods rich in magnesium. Once again that is nuts, green vegetables, dark chocolate and tofu.

    15:13 Tofu has lot of magnesium in it. So if we have low magnesium, we can have high magnesium. High magnesium, you are not going to really see a whole lot in your career.

    15:24 But that is defined as anything greater than 3 mEq/L. This is usually in your kidney failure patients who are on dialysis and once again they don't urinates, so they don't lose their electrolytes. So all that has to be done artificially through hemodialysis. Or people who like to take a lot of magnesium rich medications. These are usually your antacids. So what are the symptoms of high magnesium? Heart irregularities, confusion, muscle weakness and if left get on too long you can have temporary paralysis. So how do we treatment high magnesium? Tell the patient to stop taking so many antacids and they might need hemodialysis that help to throw out some of that or we can give IV calcium gluconate to offset the level of magnesium. Some other important lab values you are going to see on your exam are a complete blood count also known as a CBC.

    16:23 The important things that you need to look for on your CBC are red blood cells which are needed for oxygen transport. Normals are different from men and for women. In general women's CBC values are going to be a little lower.

    16:43 Because we were made different. We have less muscle than men and we have a little bit less blood flow than men.

    16:49 Another component you are going to see on your CBC are white blood cells. These are need to protect you from infection. So a white blood cell is a total number of all the things that are making up all the different types of white blood cells.

    17:04 So there could be eosinophils, granulocytes, basophils, monocytes, macrophages. All those are different types of white blood cells. But the total WBC count is going to be the total of all those things that are making that up.

    17:16 So for the NCLEX you just need to constrain yourself with the total number of WBCs. Platelets, those are needed to help your blood clot. If your platelet count is too low, you have trouble clotting. Your platelet count is too high, this can clog some of your organs especially your spleen. Hemoglobin is needed to transport oxygen into the blood. Once again the numbers are little different from men and women. Normals are little bit lower for women. And then your hematocrit is always listed as a proportion or percentage. This is the proportion of blood that consists of blood cells. Once again numbers are a little different from men and for women, usually lower for women.

    18:04 Another set of lab values that you are going to see on your NCLEX exam is an arterial blood gas report also known as ABG. This is important to tell us how well we are perfusing oxygen and carbon dioxide in our blood and how well our body is maintaining our pH balance. So the pH tells us if we are in an acidotic state or an alkalotic state. Normal blood pH is 7.35 to 7.45.

    18:34 If it's less than 7.35, it's considered to be acidotic. If it's greater than 7.45, it's considered to be alkalotic. Another number that you are going to see on this ABG report is the normal paO2. This is the amount of oxygen that is in our blood. You might see this abbreviated as pO2 also. The normal paO2 should be 80 to 100% because we want a lot of oxygen in our blood. This number can be higher than 100% if your patient is on supplement of oxygen such as a nasal cannula on a ventilator. Another number on this blood gas report is the number of carbon dioxide in our blood. So normal paCO2 is 35 to 45 mEq/L You got to remember you are blowing out your CO2. You don't want a lot of CO2 in your body.

    19:35 If your CO2 level gets too high, you get confused, you get lethargic, you get sleepy. So if these numbers are off, something is wrong with the way your patient is breathing. They are either breathing too fast, blowing off too much CO2 or they are breathing too slow and maintaining their CO2.

    19:51 And finally one of the other numbers that you'll see on this blood gas report is the bicarbonate of the blood. The bicarbonate of the blood is what helps us maintain a normal pH. So normal bicarbonate blood is 24 to 26 mEq/L. And finally another test result that you are going to see on your NCLEX exam are things called coagulation times. This tells us how well the blood is clotting. There's three basic test results that you have to remember PTT, PT, and your INR.

    20:29 So the PTT is the partial thromboplastin time. This is normally about 20 to 36 seconds. We check PTTs whenever giving somebody an IV heparin infusion. So if somebody has a blood clot, they are on an IV heparin drip you have to monitor their PTT time.

    20:51 That's how you adjust their heparin. Another is their prothrombin time.

    20:56 Normally this is 9 to 12 seconds. PTT is going to be more accurate when you administering IV heparin. And finally the INR. INR simply stands for International Normalized Ratio. This is used to monitor warfarin also known as Coumadin. The level that you want somebody's INR to be, depends on why they are getting the Coumadin. So we would like an INR usually to be anywhere from 2 to 3 or 2.5 to 3.5. I guess that is just depend on why they are on the Coumadin. So if somebody's INR times are too high, say you check their INR and its 5, that puts them at a higher risk for bleeding and in order to correct that, you give the patient vitamin K. Vitamin K can either be given IV or intramuscularly. But when an elevated INR is the reason you are giving the vitamin K, you usually give it via an IV. Thank you. This has been Jill Beavers-Kirby discussing lab values.


    About the Lecture

    The lecture Laboratory Values by Jill Beavers-Kirby is from the course Physiological Integrity. It contains the following chapters:

    • Laboratory Values
    • Electrolyes - Potassium - Hyperkalemia
    • Electrolyes - Sodium - Hypernatremia
    • Electrolytes - Calcium
    • Electrolyes - Magnesium
    • Complete Blood Count (CBC)
    • Arterial Blood Gas (ABG)
    • Coagulation Times

    Included Quiz Questions

    1. Potassium
    2. Chloride
    3. Sodium
    4. Carbon dioxide
    1. To regulate body temperature
    2. Signals muscles to contract
    3. Enables nerves to respond to stimuli
    4. Help regulate fluids
    1. 59 year-old with diaphoresis, pneumonia, and high fever
    2. 25 year-old with leukemia who is receiving chemotherapy
    3. 50 year-old with congestive heart failure who is taking Lasix
    4. 30 year-old with nausea, vomiting, and diarrhea
    1. 65 seconds
    2. 50 seconds
    3. 35 seconds
    4. 30 seconds

    Author of lecture Laboratory Values

     Jill Beavers-Kirby

    Jill Beavers-Kirby


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