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Nursing Lab Values to Know

Lab values aren’t constant, but knowing generally accepted ranges is essential for passing the NCLEX and for a career as a nurse.

To be a nurse is to know lab values. Nearly every single shift you’ll have to note, record, and assess a whole lot of data generated by your patients. This information is crucial to their health and care, and knowing how to record, manage, and interpret this data will be a big part of your career. You will also almost certainly get asked about lab values on the NCLEX.


What follows is by no means a comprehensive list of lab values. This is only a handful, but it’s a handful any nurse has to know. Many of these values will come up often both on the NCLEX and in your work.


Related Resource: 10 Common Types of NCLEX Questions

What is a lab value?

Lab values measure several variables in a patient’s body chemistry. There’s no one, main standard of lab values considered universally normal. Normal values can vary from hospital to hospital or institution to institution. As such, the NCLEX will not ask you what any normal ranges are. Instead, it will give you values that are fairly far outside the norm and then ask what course of action you’d take based on that number. Hospitals, universities, and clinics have different boundaries for normal, but grossly abnormal numbers are recognized by everyone in healthcare. That’s what the test will ask you about.


Related Resource: 6 Common NCLEX Mistakes to Avoid

Important lab values

Here’s the good stuff. The following list is a sampling of common lab values generally considered normal:


Blood gases:

pH: 7.35-7.45

PaO2: 80-100 mm Hg

PaCO2: 35-45 mm Hg

HCO3:  22-26 mEq/L

SaO2:  >95%

Total Cholesterol:  <200 mg/dL

HDL: Females:  35-80 mg/dL, Males:  35-65 mg/dL

LDL:  <130 mg/dL

Triglycerides: <150 mg/dL

WBC: 5,000 – 10,000/uL

Platelets: 150,000 – 400,000 mm3

Hemoglobin:   Females: 12-16 g/dL, Males: 14-18 g/dL

Hematocrit:     Females: 37-47%, Males:  42-52%

PT: 11-12.5 seconds (therapeutic—for someone on warfarin is 1.5-2.5 times the normal range—-16-31 seconds)

aPTT: 30-40 seconds (therapeutic—for someone on Heparin is 1.5-2 times the normal range—–45-80 seconds)

INR: 2-3 (therapeutic range for someone on warfarin). Someone not on warfarin:  0.8-1.1

D-dimer: 0-250 ng/mL (may also be reported as Positive or Negative)

Fibrinogen levels: 170-340 mg/dL

Fibrin degradation products: <10 mcg/mL

Sodium: 135-145 mEq/L

Potassium: 3.5-5 mEq/L

Chloride: 98-106 mEq/L

Calcium: 9-10.5 mg/dL

Magnesium: 1.3-2.1 mEq/L (therapeutic range—for someone on magnesium for preeclampsia—– 4-7mEq/L)

Phosphorus: 3.5-4.5 mg/dL

AST (aspartate aminotransferase): 5-40 units/L

ALT (alanine aminotransferase): 8-20 units/L

ALP (alkaline phosphatase): 42-128 units/L

Amylase: 56-90 IU/L

Lipase: 0-110 units/L

Total bilirubin: 0-1 mg/dL

Direct (conjugated) bilirubin: 0-0.3 mg/dL

Indirect (unconjugated) bilirubin: 0.1-1 mg/dL

Albumin: 3.5-5 g/dL

Prealbumin: 19-38 mg/dL

Alpha-fetoprotein: <40 mcg/L

Ammonia: 15-110 mg/dL

BUN: 10-20 mg/dL

Serum creatinine: 0.6-1.2 mg/dL

Creatinine clearance:  Females:  80-125 mL/min, Males: 90-139 mL/min

Glomerular filtration rate (GFR): 120-130 mL/min

Fasting blood glucose: <110 mg/dL

Oral glucose tolerance test: <140 mg/dL

Glycosylated hemoglobin (HbA1c):  5% or less indicates absence of diabetes mellitus; 5.7%-6.4% indicates prediabetes mellitus; 6.5% or higher indicates diabetes mellitus

T3: 70-205 ng/dL

T4: 4-12 mcg/dL

TSH: 0.4-6 microunits/mL

Urine specific gravity: 1.010-1.030


Got all that? Probably not. Each one needs to be studied and contextualized if you’re going to remember it. That kind of material is what whole classes are made up of, but something like this can be good for a quick reference.


Again, these ranges are general and there are more lab values to know. Different institutions likely have different standards for what is considered normal. There can be very good reasons for that, too. Human biochemistry can be affected by a variety of factors, such as elevation. However, it’s important that you can recognize what is obviously abnormal, both for the NCLEX and for your career.


Related Resource: 7 Essential NCLEX Study Tips

How you’ll use lab values

Knowing lab values is only the beginning. What’s more important than knowing specific ranges of the numbers, though, is knowing what to do if something is wrong. Nurses are often the first healthcare professionals to see lab values, so if any of them indicate something unusual, you’re the one who has to spring into action. Memorization is important, but so is judgement, a clear head, and knowing how to quickly and efficiently do what’s needed. At the end of the day, these numbers inform the actions of healthcare workers. Knowing them could very likely save someone’s life.


Lab values are only one thing you’ll have to learn to pass the NCLEX and become a nurse! Stay in touch with the Ameritech community by following us on Facebook and Twitter. Happy studying!

Nursing Lab Values to Know