Normal Lab Values in Nursing

Staff Writer
Apr 5, 2022 | 2 min read

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-RN and in your nursing practice.

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.

How to Use Lab Values

Knowing lab values is an essential part of providing care to patients. However, what’s more important than knowing specific ranges of the numbers 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.

NCLEX Lab Values Ever Nurse Should Know

It’s important to know that lab value questions on the NCLEX will not ask merely for normal ranges of any specific labs. Questions like this would be simple knowledge questions, and the NCLEX is written at the analysis/application level.

So, while you may see an NCLEX question that includes normal and abnormal laboratory results, the true underlying purpose of this question is to determine if you can recognize abnormal results and act on what you know. Essentially, the NCLEX wants to know if you can analyze laboratory results, recognize an abnormal result, and (most importantly) do something to fix the problem — or at least not make it worse.

Normal Lab Values

These lab value ranges are general and not comprehensive. Some of these labs may vary a little from what you’re used to. You may remember lab values can change based on where you live and work (i.e sea level vs. Mount Everest). The lab results in your hospital may be a little different, but remember this is the NCLEX hospital, at perfect elevation, in a wonderful place where you always have enough staff and resources available at all times. Don’t worry about the exact numbers. Any NCLEX question that includes labs will be out of range enough for you to notice. While human biochemistry can be affected by a variety of factors, such as elevation, it’s important that you can recognize what is obviously abnormal, both for the NCLEX and for your career.

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

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