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16 of the Most Common Lab Values New Nurses MUST Know...and how to memorize them!


When you specialize in an area of nursing, you will typically become familiar with the most common lab values you encounter and work with on a daily basis. Most often this is through constant exposure more so than intentional memorization. Still, when working on an unfamiliar unit with patients whose maladies are outside of your comfort zone, or if you are still a student studying for your exams and possibly the NCLEX, some basic lab values simply must be committed to memory the old fashion way. While these numbers can seem difficult to relate in an effort to memorize them, I have come across some tricks to help me remember them.


Sodium: Sodium has “od” making it odd, just like the numbers 1, 3, and 5. That’s why sodium is 135-145.


Potassium: Bananas are rich in potassium, and you usually buy 3 or 5 bananas in a bunch. That’s why potassium is 3.5-5.


Magnesium: Same as potassium but drop the 1. So 35-45.


PaCO2: same as magnesium, so 35-45.


pH: Same as Magnesium but with a 7. So 7.35-7.45.



BUN: Burgers come on buns and they can cost anywhere from $5 at a fast food place to $20 at a high-end restaurant. That’s why the BUN is 5-20.


Creatinine: We are trying to create a dozen, so we use six to make twelve. That’s why creatinine is 0.6-1.2.


Calcium: milk is loaded with calcium and a gallon of milk weighs 8.5 pounds. We like 2% milk, which we add to 8.5 to get 10.5. That’s why calcium is 8.5-10.5.


Bicarbonate: found in soda which we buy in 12 packs. But who wants just one 12 pack. We want double. So Bicarb is around 24 (23-29).


WBCs: Wanna Buy a Car? Spend around $4,000 to $12,000, which is why WBCs are 4K- 12k.


The rule of 3’s applies to 3 other parts of the blood count. 4.5-5 is the base number for RBCs. Times 3 and we get 15 for hemoglobin (average) and times 3 again we get 45 for hematocrit.


INR: The I in INR looks like the number 1, which is the normal value for INR.


PT: During PT, short for physical training, you do 10-12 reps per exercise. So the range for PT is 10-12.


PTT: We’re adding 2 T’s compared to the PT. So we go from 10 to 20 to 30. The range for PTT is therefore 30-40.


I hope these tricks will help you remember some of the most common and important lab values in nursing. I recommend separating them into smaller groups, perhaps by panel, ie CBC, chemistry, coagulation, and studying them repeatedly. This is one area of nursing that flashcards really can be an effective means of memorizing and, in combination with these tricks, you should have your lab values down in no time.






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