Questions involving Laboratory Values and its reference ranges are included in most nursing examinations, especially the NCLEX-RN.
Normal Lab Values in Nursing – As a nursing professional, understanding normal lab values is essential in providing quality care to patients. Lab tests are an important part of the diagnostic process, and abnormal lab values can indicate the presence of a medical condition or disease. In this article, we will provide a comprehensive guide to normal lab values for nursing professionals, including common lab tests and their associated normal ranges.
Different Types of Laboratory Tests
There are several types of laboratory tests being drawn for patients. These are usually grouped according to the type of specimens being drawn out and the primary purpose of obtaining them. Below are the most common:
1. Metabolic Tests.
These tests are done to determine the fluid and electrolyte balance of a patient as well as to check for other metabolic parameters like blood glucose, protein, and liver enzymes. These can either be basic (also termed as BMP) or comprehensive (normally written as CMP).
a. BMP. A basic metabolic panel is usually done as part of a routine physical examination and includes 8 different tests. These are:
- Glucose
- Calcium
- Sodium
- Chloride
- Potassium
- CO2
- Blood Urea Nitrogen (BUN) and
- Creatinine
b. CMP. Or a complete metabolic panel includes all of the tests that are part of the BMP plus liver function tests. In total, there are 15 tests that comprise the CMP: 8 from BMP and additional 7 tests, which are:
- ALP
- AST
- ALT
- Bilirubin,
- Total Protein
- Albumin; and
- Globulin.
2. Complete Blood Counts.
Usually written as CBC, this test aims to determine the number or number of cells in the patient’s blood sample. Over 15 different parameters can be determined from the CBC; however, only some of them are commonly included in requests. These include:
a. Haemoglobin. the protein component of the red blood cells that help carry oxygenated blood throughout the body.
b. Haematocrit. This component determines the total amount of red blood cells present in a sample as compared to the total circulating blood volume. It is a good indicator of the hydration status of an individual.
c. White Blood Cells (WBC). The presence of WBC determines the ability of the body to fight off infections. An increased WBC count may indicate the presence of an infection, inflammation, or other conditions that may cause the body to produce additional white blood cells such as stress or an adverse effect on medications. Lowered WBC levels, on the other hand, may indicate immunosuppression. There are 5 types of WBCs that may be determined by a CBC:
- Monocytes– responsible for fighting off infection and foreign bodies.
- Eosinophils– responsible for the allergic responses of the body and may also be increased during parasitic infections.
- Neutrophils– the components that help fight off bacterial infections.
- Basophils– also responsible for functioning during allergic responses or inflammation.
- Lymphocytes– plays a role in guarding the body off from viral infections.
d. Red blood cell indices. These are various tests that determine the other components present in RBCs and help to diagnose further other conditions such as specific types of anaemia, blood cell size, and cellular integrity.
- Mean Corpuscular Volume (MCV). This helps determine the actual size of the red blood cells and can be useful in ruling out the presence of megaloblastic anaemia.
- Mean Corpuscular Haemoglobin (MCH). Specifically, it helps determine the amount of haemoglobin in a red blood cell and is useful in caring for patients with iron-deficiency anaemia.
- Red Cell Distribution Width (RDW). A test that helps measure the variation in the size of red blood cells in a sample.
e. Platelets. These blood components are responsible for clotting and usually measured among patients with bleeding or clotting problems. Lower values indicate bleeding tendencies, while elevated values are responsible for clotting problems.
3. Coagulation Studies.
These tests help assess the presence of bleeding problems and are more specific than the platelet counts, which are done as part of the CBC. These are usually done for patients with haemolytic conditions or are taking anticoagulants.
- PTT
- INR
- αPTT
4. Urine analysis (urinalysis).
Usually done as part of routine tests for patients admitted, this helps determine the presence of urinary tract infections, potential kidney damage, and hydration status of a patient. It also helps determine the response of a patient with urinary tract infections to treatment regimens.
5. Arterial Blood Gases.
ABGs are important to assess not only the fluid and electrolyte balance of the patients, but these values also help evaluate the presence of respiratory and metabolic conditions of patients.
6. Lipid Profile.
These tests determine the amounts of cholesterol, triglycerides, and other lipoproteins in a blood sample and help determine the risks a patient has for coronary artery diseases.
7. Haemoglobin A1C.
Usually performed to determine whether a patient can be diagnosed with diabetes, HbA1C measures patients’ blood glucose levels over a 3–4-month period. This time period is also the same length as the life cycle of a red blood cell. This test also helps determine a patient’s adherence to the treatment regimen or his response to therapy.
8. Tests to measure drug levels in the blood.
Certain medications have to be monitored for therapeutic levels in the bloodstream and have to be watched for the risk of overdose. Common among these drugs are cardiac glycosides, lithium, carbamazepine, Dilantin, and some emergency drugs.
Below is a table that includes the most commonly performed laboratory tests and normal ranges
| Test | Abbreviation | Adult | Child |
|---|---|---|---|
| URINALYSIS | |||
| Colour | N/A | Pale Yellow to Amber | Same as adults |
| Odor | N/A | Aromatic | Same as adults |
| Turbidity | N/A | Clear | Same as adults |
| Specific Gravity | Sp. Gr. | 1.016 to 1.022 | Same as adults |
| pH | pH | 4.5 to 7.8 | Same as adults |
| Glucose | N/A | >0.5 g/day | Same as adults |
| Red Blood Cells | RBC | less than 3 cells/HPF | Same as adults |
| White Blood Cells | WBC | less than or = 4 cells/HPF | Same as adults |
| Bacteria | N/A | None or >1000/ml | Same as adults |
| Casts | N/A | None to few | Same as adults |
| Crystals | N/A | None | Same as adults |
| Uric Acid | N/A | 250 to 750 mg/24 hours | Same as adults |
| Sodium | Na | 40 to 220 mEq/24 hour | Same as adults |
| Potassium | K | 25 to 125 mEq/24 hours | Same as adults |
| Magnesium | Mg | 7.3 – 12.2 mg/dL | Same as adults |
| HEMATOLOGIC – COMPLETE BLOOD COUNT (CBC) | |||
| Haemoglobin** | Hgb | Male: 14-18 g/dL Female: 12-16 g/dL Pregnant: less than 11 g/dL | 1-6 yr: 9.5-14 g/dL 6-18 yr: 10-15.5 g/dL |
| Haematocrit** | Hct | Male: 42-52% Female: 37-47% Pregnant: >33% | 1-6 yr: 30-40% 6-18 yr: 32-44% |
| White Blood Cell** | WBC | Both Sexes: 5-10 mm3 | ≤2yr: 6.2-17 mm3 ≥2 yr: 5-10 mm3 |
| Platelet Count** | PLT | Both Sexes: 150-400 mm3 | Same as adults |
| Mean Corpuscular Volume | MCV | 80-100 fl | Same as adults |
| Red Blood Cell Distribution Width | RDW | 11.5% to 14.5% | Same as adults |
| Mean Corpuscular Haemoglobin Concentration | MCHC | 30-35g/dL | Same as adults |
| Mean Corpuscular Haemoglobin | MCH | 0.4-0.5 fmol/cell | Same as adults |
| Neutrophils | N/A | 2-8 x 10^9/L | Same as adults |
| Lymphocytes | N/A | 1-4 x 10^9/L | Same as adults |
| Monocytes | N/A | 0.2-0.8 x 10^9/L | Same as adults |
| Eosinophils | N/A | less than 0.5 x 10^9/L | Same as adults |
| Basophils | N/A | 0–2% cells/mm³ | Same as adults |
| ARTERIAL BLOOD GASES (ABGs) | |||
| Partial pressure of oxygen | PaO2 | 75 – 100 mmHg | Same as adults |
| Partial pressure of carbon dioxide | PaCO2 | 38 – 42 mmHg | Same as adults |
| Arterial blood pH | pH | 7.38 – 7.42 | Same as adults |
| Oxygen saturation | SaO2 | 94 – 100% | Same as adults |
| Bicarbonate | HCO3 | 22 – 28 mEq/L | Same as adults |
| HEMATOLOGIC – COAGULATION PANEL (COAGS) | |||
| Prothrombin Time | PT | Both Sexes: 11-12.5 sec Pregnant: decreased 1.5-2.5 times the normal control (on Coumadin) | Same as adults |
| International Normalized Ratio | INR | Normal is 0.9-1.2 seconds Desirable therapeutic level is 2-3 times the normal | Same as adults |
| Partial thromboplastin time | PTT | Both Sexes 60-70 sec Pregnant: decreased 1.5-2.5 times the normal control (on Heparin) | Same as adults |
| Activated partial thromboplastin time | APT | Both Sexes 30-40 sec 1.5-2.5 times the normal control (on Heparin) | Same as adults |
| BLOOD CHEMISTRY – BASIC METABOLIC PANEL (BMP) | |||
| Glucose | Glu | Both Sexes: 70-110 mg/dL | ≤2 yr: 60-100 mg/dL ≥2 yr: 70-110 mg/dL |
| Sodium | Na | Both Sexes: 135-145 mEq/L | Same as adults |
| Potassium | K | Both Sexes: 3.5-5 mEq/L | 3.4-4.7 mEq/l |
| Creatinine | N/A | Male: 0.6-1.2 mg/dL Female: 0.5-1.1 mg/dL | Child: 0.3-0.7 mg/dL |
| Chloride | Cl | Both Sexes: 95-105mmol/L | |
| Blood Urea Nitrogen** | BUN | Both Sexes: 10-20 mg/dL | 5-18 mg/dL |
| BLOOD CHEMISTRY- COMPLETE METABOLIC PANEL (CMP) | |||
| Alkaline Phosphatase | ALP | 40-120 U/L | |
| Asparatate Transaminase | AST | 10-40 U/L | |
| Alanine Transaminase | ALT | 7 to 56 U/L | |
| Bilirubin | N/A | 2-20 µmol/L | |
| Total Protein | CHON | 60-80 g/L | |
| Albumin | Alb | 35-50 g/L | |
| Globulin | N/A | IgM Component: 2.0-3.5 g/dL IgG Component: 75-300 mg/dL | |
| BLOOD CHEMISTRY – LIPID PROFILE | |||
| Cholesterol** | N/A | Both Sexes: less than 200 mg/dL | 120-200 mg/dL |
| Low-Density Lipoprotein | LDL | Both Sexes: less than 100 mg/dL | |
| High-Density Lipoprotein | HDL | Both Sexes: 40-60 mg/dL | |
| Triglycerides | TG | Both Sexes: less than 150 mg/dL | |
| BLOOD CHEMISTRY – MISCELLANEOUS | |||
| Glycosylated Haemoglobin** | Hgb A1C | less than 6% | Same as adults |
| THERAPEUTIC BLOOD LEVELS OF DRUGS | |||
| Digoxin | N/A | Both Sexes: 0.5-2ng/mL | |
| Carbamazepine | N/A | Both Sexes: 4-10 mcg/mL | |
| Gentamycin | N/A | 5-10 mcg/mL (during peak); less than 2.0mcg/mL (valley) | |
| Lithium | Li | 0.8-1.5 mEq/L; critical 2.0 mEq/L | |
| Phenobarbital | N/A | 15-40 mcg/mL | |
| Phenytoin | N/A | 10-20 mcg/dL | |
| Theophylline | 10-20 mcg/dL | ||
| Tobramycin | 5-10 mcg/mL (peak); 0.5-2.0 mcg/mL (valley) | ||
| Valproic Acid | 50-100 mcg/mL | ||
| Vancomycin | 20-40 mcg/mL (peak); 5-15 mcg/mL (trough | ||
| Table 1. Commonly performed Laboratory Tests and Reference Values. (NOTE: Blank spaces for children’s’ results vary according to age of the child.) | |||
Obtaining Samples from the Patient
Like any other procedure, you should remember that obtaining blood samples from a patient requires informed consent. Once this is obtained, you can then proceed to collect the specimen needed or prepare the patient for it. The following reminders should be observed:
1. Coordinate specimen collection with the laboratory. This helps in preserving the viability of the specimen and ensure that no sample goes to waste.
2. Prepare the patient for sample collection.
- If the specimen to be collected needs the patient to fast for 8-12 hours, inform him beforehand.
- Explain once again the test to be conducted and the specimen needed to be collected.
- Prepare the site where the specimen would be collected from. Cleanse with prescribed antiseptic if needed.
3. Instruct the patient what to do as the specimen is collected.
Sampling Procedure
Blood collection or collecting a specimen sample involves the drawing of blood used for laboratory testing.
Blood specimen collection or collecting blood specimens is a blood sample is taken by a healthcare provider in a laboratory or hospital setting for laboratory analysis or a blood sample is sent to a laboratory for analysis.
To collect blood specimens Blood collection tube is used for collecting blood samples.
Peripheral Vein
If collecting a peripheral vein sample:
- Ask the patient to clench his hands and make a fist.
- Locate the vein and pull the skin in the opposite direction.
- Carefully insert the needle with the bevel facing up. Make sure that an angle of 15-30 degrees is observed as the needle is inserted.
- Allow the blood to fill the syringe up to the desired level.
- Remove the needle swiftly and apply pressure on the puncture site using a sterile gauze pad.
- Secure the gauze with a bandage.
- Transfer the blood sample to the prescribed tubing and label it appropriately.
- Send the sample to the laboratory for analysis.
Central line
If the specimen is to be collected from a central line:
- Wipe the port where the specimen is to be collected using a 70% alcohol solution.
- Allow the port to air dry for a few seconds.
- Draw out a few millilitres of blood from the port and discard.
- Draw the intended amount of blood sample from the port and label it appropriately.
- Flush out the port with 15-20mL of saline solution.
- Send the specimen to the laboratory for analysis.
Arterial Blood Gas
If obtaining an arterial blood gas sample:
- Instruct the patient that the vessel to be used in obtaining a sample is arterial, and the appearance of the blood may be brighter than the venous sample.
- Place the patient’s palm up on a flat surface and position the wrist dorsiflexed at 45 degrees.
- If the artery cannot easily be accessed at this position, place a towel or small pillow under the wrist for additional support.
- Cleanse the puncture site with an antiseptic solution. This may either be 70% alcohol or iodine solution, depending on facility policy.
- Air-dry the site for a few seconds and apply a local anaesthetic such as a 2% lidocaine solution.
- Palpate the pulse and puncture the site using a pre-heparinized syringe with a 23- or 25-gauge needle. Ensure that a 15–30-degree angle is obtained.
- Draw up the recommended amount of blood sample and firmly place a sterilized gauze over the puncture site before withdrawing the needle.
- Apply pressure over the site for at least 10-15 minutes to prevent bleeding.
- Label the sample appropriately and send it to the laboratory for analysis.
- If the sample cannot be immediately sent out, place it on a carrier filled with ice. The specimen would still be viable for a couple of hours, and the accuracy of the results would not be compromised.
- Monitor the patients for signs of complications such as prolonged bleeding, infection, arteriospasm, or thrombosis.
Urine Specimen
For obtaining a urine specimen, give the patient the following instructions:
- Inform what type of urine specimen would be collected. The most common method, however, is the midstream clean-catch specimen.
- Instruct to clean the perineal area and cleanse the urethral opening. Use downward strokes in cleaning.
- Ask to start the urinary stream, void a little to clean the urethral opening. (Note: the sample is not yet collected at this point).
- Stop the flow temporarily and hold the collection container below the urethral opening and continue voiding.
- Once the desired amount of sample is collected, seal the container.
- Collect the specimen from the patient, label it appropriately, and send it for analysis.
- If collecting from a catheter: Cleanse the collection port and insert the needle. Aspirate the desired amount of specimen. Transfer the specimen to the container, label, and send out for analysis.
How to remember normal laboratory values for Nurses
Remembering normal lab values in nursing can be challenging, but here are some strategies that may help to remember normal lab values in nursing :
- Repetition: Repetition is key when it comes to memorizing lab values. Review the lab values regularly, and try to memorize them in small groups or categories, such as electrolytes or blood gases.
- Mnemonics: Mnemonics are memory aids that can help you remember lab values. For example, you could use the mnemonic “Never Let Monkeys Eat Bananas” to remember the normal ranges for sodium (135-145 mEq/L), potassium (3.5-5.0 mEq/L), and calcium (8.5-10.5 mg/dL).
- Visualization: Visualizing the lab values can help you remember them. For example, you could picture a blood pressure cuff (normal range 90-120 mmHg) or a thermometer (normal range 97-99°F) to help you remember those values.
- Practice questions: Practice questions can help reinforce your knowledge of lab values. You can find practice questions in nursing textbooks, review books, or online nursing resources.
- Clinical experience: Clinical experience can help you become more familiar with lab values and their significance in patient care. As you care for patients, pay attention to their lab values and how they correlate with their clinical status.
Nursing Implications
1. Relay all results to the physician as soon as they are available. Note significantly increased or decreased values, as well as formerly abnormal values that have normalized.
2. Compare previous results with present ones, if available. This helps in evaluating the care plan being implemented.
3. Observe patient preparation for tests to be conducted. Please note that some tests may have special considerations for patient preparation especially when they are under specific types of medication. For example:
- Occult Blood Test: Withholding iron supplements and dark-colored foods at least 3 days before testing.
- Lipid Profile, Fasting Blood Glucose: NPO at least 8-12 hours prior to drawing up of blood samples.
- Coagulation studies: Temporarily withholding anticoagulants to patients at least 72 hours prior to testing.
- Patients undergoing a test using dye: Assessment for allergy to iodine or other substances used as contrast media.
4. Determine patients’ risk for bleeding, infection, and other complications that may arise due to the collection of specimens and plan to avoid them.
5. Provide the patient and his significant others education about the testing, how the sample will be collected and the care needed to be provided to the patient before and after.
6. Ensure the viability of the sample being collected. Make sure that it is obtained from the right site, following the collection instructions, and sent to be analyzed in the prescribed time.
7. Provide care to the patient after specimen collection.
REFERENCES
- Basavanthappa, B., (2015). Medical Surgical Nursing. New Delhi: Jaypee Brothers Medical Publishers.
- Billings, D. and Hensel, D., 2019. Lippincott Q & A Review For NCLEX-RN. 13th ed. St. Louis, MO., USA.: Wolters Kluwer Medical.
- Hinkle, J.L. & Cheever, K.H. (2018). Brunner & Suddarth’s Textbook of Medical-Surgical Nursing (14th ed.). Philadelphia: Wolters Kluwer.
- Morton, P., & Fontaine, D. (2018). Critical Care Nursing. Wolters Kluwer.
- Potter, P.A., Perry, A.G., Stockert, P.A., & Hall, A.M. (2019). Essentials for Nursing Practice (9th ed.). St. Louis: Elsevier
Stories are the threads that bind us; through them, we understand each other, grow, and heal.
JOHN NOORD
Connect with “Nurses Lab Editorial Team”
I hope you found this information helpful. Do you have any questions or comments? Kindly write in comments section. Subscribe the Blog with your email so you can stay updated on upcoming events and the latest articles.
