Normal lab values for the NCLEX
Checked October 15, 2026 · 31 tests · adults
Learn the adult range for each test below, then always read the range on the client's own report, because labs differ a little. Start with potassium, sodium, fasting glucose, pH and the INR target on warfarin. Every value names its source.
Know these first
- Sodium (Na⁺)
- Potassium (K⁺)
- Fasting blood glucose
- Platelets
- INR2.0–3.0 on warfarin
- pH
Self-test on: guess each range, then tap it to check.
Electrolytes
- Potassium (K⁺)
- Too high or too low can cause dangerous heart rhythms. MedlinePlus lists 3.7–5.2 mEq/L.
- Open RN 1
- Bicarbonate (total CO₂)
- Usually part of a basic metabolic panel. The ABG bicarbonate (HCO₃⁻) has its own range below.
- MedlinePlus 3
Kidney and urine
Glucose
Blood count (CBC)
Clotting
Arterial blood gas (ABG)
Liver and protein
Drug levels
- Lithium
- Draw the level 10–12 hours after the last dose. Toxicity signs can start at 1.5 mEq/L. Above 2.5 mEq/L is an emergency.
- Open RN 24
Adult reference ranges. Each row names its source. Labs and textbooks differ a little, so the range on the client's own report always wins. Units here are the U.S. units used on NCLEX-style items (mEq/L, mg/dL). For exam study only, not medical advice.
Check yourself: 10 questions
Normal lab values quiz
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Questions are original practice items written to the published exam content, not real exam questions.
The nurse reviews a client's morning electrolyte results. Which result is within the normal range?
Correct answer: D
Compare each value with the range printed next to it. Only the potassium falls inside its range. The sodium, calcium and magnesium are all below range and need follow-up.
- A A sodium of 132 mEq/L is below the 136–145 mEq/L range (hyponatremia).
- B A calcium of 7.9 mg/dL is below the 8.6–10.2 mg/dL range (hypocalcemia).
- C A magnesium of 1.4 mg/dL is below the 1.7–2.2 mg/dL range (hypomagnesemia).
- D Correct: 4.2 mEq/L is inside the 3.5–5.1 mEq/L potassium range.
Learn this topic: Which lab values should make a nurse act right away? 5-minute lesson
Source: Open RN Nursing Fundamentals 2e, 15.4 Electrolytes · MedlinePlus: Magnesium blood test ·
A client with heart failure takes digoxin and furosemide. Today's results are potassium 3.1 mEq/L (3.5–5.1 mEq/L) and digoxin 1.2 ng/mL (0.8–2.0 ng/mL). Why does the nurse report the potassium result promptly?
Correct answer: B
Safety first: hypokalemia increases the effect of digoxin and can lead to digoxin toxicity, even when the digoxin level itself is in range. A potassium below 3.5 mEq/L in a client on digoxin should be reported to the provider right away.
- A The risk with low potassium is a stronger digoxin effect and toxicity, not a false lab value.
- B Correct: hypokalemia increases digoxin's effect and the risk of toxicity, so it must be reported.
- C The digoxin level of 1.2 ng/mL is inside the 0.8–2.0 ng/mL range, so nothing suggests the dose is too low.
- D Diuretics that waste potassium can lower it, but a low potassium is not safe for a client taking digoxin.
Learn this topic: Which lab values should make a nurse act right away? 5-minute lesson
Source: Open RN Nursing Pharmacology, 6.7 Cardiac Glycosides · Open RN Nursing Fundamentals 2e, 15.4 Electrolytes ·
The nurse reviews four abnormal results. For each result, indicate what it mainly tells the nurse about.
Kidney function Liver cell injury Breathing (CO₂ removal) Bleeding risk Creatinine 2.1 mg/dL (0.7–1.3 mg/dL for males) ALT 112 U/L (4–36 U/L) PaCO₂ 54 mm Hg (35–45 mm Hg) Platelets 48,000/mcL (150,000–400,000/mcL) Select one option in each row.
Correct answer: Creatinine 2.1 mg/dL (0.7–1.3 mg/dL for males): Kidney function; ALT 112 U/L (4–36 U/L): Liver cell injury; PaCO₂ 54 mm Hg (35–45 mm Hg): Breathing (CO₂ removal); Platelets 48,000/mcL (150,000–400,000/mcL): Bleeding risk
Link each lab to the organ or process it reflects. The kidneys remove creatinine, ALT leaks from injured liver cells, the lungs control PaCO₂ through breathing rate and depth, and a low platelet count raises the risk of bleeding.
- Creatinine 2.1 mg/dL (0.7–1.3 mg/dL for males) Kidney function: creatinine is removed by the kidneys, so a high level suggests the kidneys are not working well.
- ALT 112 U/L (4–36 U/L) Liver cell injury: ALT is an enzyme found mostly in the liver and is released into the blood when liver cells are injured.
- PaCO₂ 54 mm Hg (35–45 mm Hg) Breathing: the lungs regulate CO₂ by changing the rate and depth of breathing, so a high PaCO₂ means CO₂ is not being removed.
- Platelets 48,000/mcL (150,000–400,000/mcL) Bleeding risk: below 50,000/mcL, bleeding can happen even with everyday activities.
Learn this topic: Which lab values should make a nurse act right away? 5-minute lesson
Source: MedlinePlus: Creatinine blood test · MedlinePlus: Alanine transaminase (ALT) blood test · Open RN Nursing Fundamentals 2e, 15.5 Acid-Base Balance · MedlinePlus: Platelet count ·
A female client's results are WBC 15,200/mcL (4,500–11,000/mcL), hemoglobin 13.9 g/dL (12.1–15.1 g/dL for females) and platelets 260,000/mcL (150,000–400,000/mcL). The result outside the normal range is the , which can be a sign of .
Choose the best option from each list to complete the sentence.
Correct answer: WBC count; infection
Only the WBC count is outside its range. A high WBC count (leukocytosis) can be caused by infection, most often bacterial, as well as inflammation, stress or some medicines.
- The WBC count of 15,200/mcL is above 11,000/mcL; the hemoglobin and platelets are both within range.
- Infection is a common cause of a high WBC count. This client's hemoglobin and platelets are normal, which does not point to anemia or a bleeding problem.
Learn this topic: Which lab values should make a nurse act right away? 5-minute lesson
Source: MedlinePlus: WBC count · MedlinePlus: Hemoglobin · MedlinePlus: Platelet count ·
A client who does not take warfarin or other blood thinners has an INR of 1.6 (0.8–1.1). How should the nurse interpret this result?
Correct answer: C
For a client not taking a blood thinner, the normal INR is 0.8–1.1. An INR above 1.1 means the blood is clotting more slowly than normal. The 2.0–3.0 target applies only to clients taking warfarin.
- A A higher INR means slower clotting, not faster clotting.
- B The 2.0–3.0 target is for clients on warfarin; this client takes no blood thinner, so 0.8–1.1 applies.
- C Correct: an INR above 1.1 in a client not taking warfarin means the blood clots more slowly than normal.
- D The INR measures clotting time; the platelet count is a separate test.
Learn this topic: Which lab values should make a nurse act right away? 5-minute lesson
Source: MedlinePlus: Prothrombin time (PT) ·
A client with no history of diabetes has an A1C of 6.1% (normal: below 5.7%). How should the nurse interpret this result?
Correct answer: B
When A1C is used to screen for diabetes, below 5.7% is normal, 5.7% to 6.4% is prediabetes and 6.5% or higher is diabetes. A result of 6.1% falls in the prediabetes range.
- A 6.1% is above the normal cutoff of below 5.7%.
- B Correct: 6.1% is inside the 5.7%–6.4% prediabetes range.
- C The diabetes range starts at 6.5%.
- D A1C reflects average blood sugar over time; a high A1C does not mean low blood sugar.
Learn this topic: Which lab values should make a nurse act right away? 5-minute lesson
Source: MedlinePlus: A1C test ·
The nurse reviews results for a female client. Which results are outside the normal range for this client? Select all that apply.
Select all that apply.
Correct answer: B, C, D
Some ranges differ by sex, so use the female range for a female client. The creatinine and hematocrit would be normal for a male but are high for a female, and the WBC count is above range for everyone.
- A 12.6 g/dL is inside the female range of 12.1–15.1 g/dL, even though it would be low for a male.
- B Outside: 1.2 mg/dL is above the female range of 0.5–0.95 mg/dL.
- C Outside: 13,200/mcL is above 11,000/mcL.
- D Outside: 46% is above the female range of 34%–43%.
- E 210,000/mcL is inside the 150,000–400,000/mcL range.
- F 4.6 million/mcL is inside the female range of 3.8–5.1 million/mcL.
Learn this topic: Which lab values should make a nurse act right away? 5-minute lesson
Source: MedlinePlus: Hemoglobin · MedlinePlus: Creatinine blood test · MedlinePlus: WBC count · MedlinePlus: Hematocrit · MedlinePlus: Platelet count · MedlinePlus: RBC count ·
A client has a urine specific gravity of 1.034 (1.005–1.030) and a BUN of 24 mg/dL (6–20 mg/dL). Which condition do these results most likely point to?
Correct answer: D
Both results are high. Loss of body fluid (dehydration) can raise urine specific gravity because the urine is concentrated, and it can also raise the BUN. Dehydration is the only choice that fits both results.
- A Drinking too much fluid lowers urine specific gravity and can lower the BUN.
- B Liver failure is a cause of a low BUN, not a high one.
- C Diabetes insipidus causes dilute urine with a low specific gravity.
- D Correct: dehydration can raise both urine specific gravity and BUN.
Learn this topic: Which lab values should make a nurse act right away? 5-minute lesson
Source: MedlinePlus: Urine specific gravity test · MedlinePlus: BUN - blood test ·
The nurse reviews laboratory results for four clients. Which result should the nurse report to the provider first?
Correct answer: B
Report the result with the greatest immediate risk to life first. A lithium level above 2.5 mEq/L is a medical emergency, even if the client has no symptoms. The other results are only slightly outside their ranges.
- A A BUN slightly above range needs follow-up, but it is not as urgent as a toxic lithium level.
- B Correct: a lithium level above 2.5 mEq/L is a medical emergency, even without symptoms.
- C A slightly low albumin needs follow-up, but it is not an emergency.
- D A slightly high bilirubin needs follow-up, but it is not as urgent as lithium toxicity.
Learn this topic: Which lab values should make a nurse act right away? 5-minute lesson
Source: Open RN Nursing: Mental Health and Community Concepts 2e, 6.4 Mood Stabilizers · MedlinePlus: BUN - blood test · MedlinePlus: Albumin blood (serum) test · MedlinePlus: Bilirubin blood test ·
A client's sodium is 128 mEq/L (136–145 mEq/L). Which findings should the nurse watch for?
Correct answer: A
Low sodium (hyponatremia) mainly affects the brain. Watch for headache and confusion, which can progress to coma.
- A Correct: headache and confusion are signs of hyponatremia.
- B Chvostek and Trousseau signs point to low calcium, not low sodium.
- C Hunger and sweating are signs of low blood sugar.
- D Visual changes such as halos are a sign of digoxin toxicity.
Learn this topic: Which lab values should make a nurse act right away? 5-minute lesson
Source: Open RN Nursing Fundamentals 2e, 15.4 Electrolytes · MedlinePlus: Low blood sugar · Open RN Nursing Pharmacology, 6.7 Cardiac Glycosides ·
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Sources
- Open RN Nursing Fundamentals 2e, 15.4 Electrolytes Accessed October 15, 2026
- MedlinePlus: Chloride test - blood Accessed October 15, 2026
- MedlinePlus: CO2 blood test Accessed October 15, 2026
- MedlinePlus: Magnesium blood test Accessed October 15, 2026
- MedlinePlus: Phosphorus blood test Accessed October 15, 2026
- MedlinePlus: BUN - blood test Accessed October 15, 2026
- MedlinePlus: Creatinine blood test Accessed October 15, 2026
- MedlinePlus: Urine specific gravity test Accessed October 15, 2026
- MedlinePlus: Blood sugar test Accessed October 15, 2026
- MedlinePlus: Low blood sugar Accessed October 15, 2026
- MedlinePlus: A1C test Accessed October 15, 2026
- MedlinePlus: WBC count Accessed October 15, 2026
- MedlinePlus: RBC count Accessed October 15, 2026
- MedlinePlus: Hemoglobin Accessed October 15, 2026
- MedlinePlus: Hematocrit Accessed October 15, 2026
- MedlinePlus: Platelet count Accessed October 15, 2026
- MedlinePlus: Prothrombin time (PT) Accessed October 15, 2026
- MedlinePlus: Partial thromboplastin time (PTT) Accessed October 15, 2026
- Open RN Nursing Fundamentals 2e, 15.5 Acid-Base Balance Accessed October 15, 2026
- MedlinePlus: Albumin blood (serum) test Accessed October 15, 2026
- MedlinePlus: Bilirubin blood test Accessed October 15, 2026
- MedlinePlus: Comprehensive metabolic panel Accessed October 15, 2026
- Open RN Nursing Pharmacology, 6.7 Cardiac Glycosides Accessed October 15, 2026
- Open RN Nursing: Mental Health and Community Concepts 2e, 6.4 Mood Stabilizers Accessed October 15, 2026
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