The normal adult ranges most often tested on the NCLEX-RN, what an abnormal result means for your client, and free practice questions to check yourself.
Ranges are typical adult values used in nursing education. Each laboratory sets its own reference ranges, so always use the range your facility or the question provides.
| Test | Typical adult range | Why it matters on the NCLEX |
|---|---|---|
| Sodium (Na) | 135–145 mEq/L | Low or high sodium changes neurologic status. Watch for confusion and seizures, and correct slowly. |
| Potassium (K) | 3.5–5.0 mEq/L | Both low and high potassium cause dysrhythmias. Hyperkalemia: peaked T waves. Hypokalemia: U waves and higher risk of digoxin toxicity. |
| Chloride (Cl) | 98–106 mEq/L | Usually moves with sodium and affects acid-base balance. |
| Calcium, total (Ca) | 9.0–10.5 mg/dL | Low calcium: tetany and positive Chvostek and Trousseau signs. High calcium: muscle weakness and kidney stones. |
| Magnesium (Mg) | 1.3–2.1 mEq/L | High magnesium (for example during magnesium sulfate therapy) depresses deep tendon reflexes and respirations. |
| Phosphorus (P) | 3.0–4.5 mg/dL | Moves opposite to calcium. Often high in chronic kidney disease. |
| Test | Typical adult range | Why it matters on the NCLEX |
|---|---|---|
| Hemoglobin (Hgb) | Male 14–18 g/dL; female 12–16 g/dL | Low values mean anemia or bleeding. Check for tachycardia, pallor, and fatigue. |
| Hematocrit (Hct) | Male 42–52%; female 37–47% | Rises with dehydration and falls with bleeding or fluid overload. |
| White blood cells (WBC) | 5,000–10,000/mm³ | High suggests infection or inflammation. Low means infection risk: use neutropenic precautions. |
| Platelets | 150,000–400,000/mm³ | Below about 50,000/mm³, bleeding risk rises: avoid injections and use bleeding precautions. |
| Test | Typical adult range | Why it matters on the NCLEX |
|---|---|---|
| Prothrombin time (PT) | 11–12.5 seconds | Monitors warfarin therapy along with the INR. |
| INR | 0.8–1.1 (no anticoagulant) | Warfarin target is usually 2–3, and higher for some mechanical heart valves. Vitamin K reverses warfarin. |
| aPTT | 30–40 seconds | Monitors IV unfractionated heparin; a common target is 1.5–2.5 times control. Protamine reverses heparin. |
| Test | Typical adult range | Why it matters on the NCLEX |
|---|---|---|
| pH | 7.35–7.45 | Below 7.35 is acidosis; above 7.45 is alkalosis. |
| PaCO₂ | 35–45 mm Hg | The respiratory part. High PaCO₂ with low pH is respiratory acidosis. |
| HCO₃⁻ (bicarbonate) | 22–26 mEq/L | The metabolic part. Low HCO₃⁻ with low pH is metabolic acidosis. |
| PaO₂ | 80–100 mm Hg | Below 80 mm Hg is hypoxemia. |
| SaO₂ | 95–100% | Interpret with the client's baseline; some clients with COPD have a lower target. |
| Test | Typical adult range | Why it matters on the NCLEX |
|---|---|---|
| BUN | 10–20 mg/dL | Rises with dehydration, GI bleeding, and kidney injury. |
| Creatinine | 0.5–1.2 mg/dL | The better marker of kidney function. Check it before nephrotoxic drugs and contrast. |
| Fasting blood glucose | 70–99 mg/dL | Below 70 mg/dL is hypoglycemia: treat it right away. 126 mg/dL or higher on two tests suggests diabetes. |
| Hemoglobin A1C | Below 5.7% | 5.7–6.4% is prediabetes and 6.5% or higher is diabetes. Shows average glucose over about 3 months. |
| Test | Typical adult range | Why it matters on the NCLEX |
|---|---|---|
| Digoxin | 0.5–2.0 ng/mL | Many heart failure guidelines aim for the low end. Toxicity: nausea, vision changes, and bradycardia, made worse by low potassium. |
| Lithium | 0.6–1.2 mEq/L (maintenance) | Narrow range. Dehydration and low sodium raise levels; above about 1.5 mEq/L signs of toxicity appear. |
| Phenytoin | 10–20 mcg/mL | Toxicity causes nystagmus, ataxia, and confusion. |
| Test | Typical adult range | Why it matters on the NCLEX |
|---|---|---|
| Albumin | 3.5–5.0 g/dL | Low albumin points to poor nutrition or liver disease, and to edema. |
| BNP | Below 100 pg/mL | Higher values support a diagnosis of heart failure. |
| Troponin | Below the lab's 99th percentile cutoff | A rise and fall above the cutoff means myocardial injury, such as a heart attack. Ranges depend on the assay. |
| Total cholesterol | Below 200 mg/dL | Part of cardiovascular risk assessment along with LDL and HDL. |
| Urine specific gravity | 1.005–1.030 | High suggests dehydration; low suggests overhydration or diabetes insipidus. |
A client with sepsis is oozing from IV sites and has a falling platelet count, low fibrinogen, and an elevated D-dimer. What does the nurse suspect?
Correct answer: A
DIC involves widespread clotting that consumes platelets and clotting factors, leading to bleeding. Low platelets and fibrinogen with high D-dimer and prolonged clotting times are typical. Treatment targets the cause.
Source: ISTH. Guidance for Diagnosis and Treatment of DIC (2013)
An older adult with dementia who can't get to water easily has a serum sodium of 154 mEq/L. Which findings does the nurse expect?
Correct answer: A
Hypernatremia usually results from water loss or inadequate intake and causes thirst, dry mucous membranes, restlessness, and confusion. Correction is gradual.
Source: Lewis's Medical-Surgical Nursing, 13th ed. (hypernatremia)
A client's potassium is 2.8 mEq/L. Which ECG change does the nurse expect?
Correct answer: C
Hypokalemia causes flattened T waves, U waves, and ST depression, and increases the risk of dysrhythmias, especially with digoxin.
Source: Lewis's Medical-Surgical Nursing, 13th ed. (hypokalemia)
A nursing student about to take an exam feels alert, focused, and slightly restless. Which level of anxiety is this?
Correct answer: C
Mild anxiety sharpens the senses and can motivate learning. Moderate anxiety narrows focus. Severe anxiety and panic impair functioning.
Source: Varcarolis' Foundations of Psychiatric-Mental Health Nursing, 10th ed.
A client is scheduled for an oral glucose tolerance test. What should the nurse teach?
Correct answer: D
The OGTT is done after an overnight fast. During the test, clients stay seated and avoid eating, smoking, and exercise.
Source: ADA. Standards of Care in Diabetes, Section 2 (diagnosis)
A client newly diagnosed with type 2 diabetes keeps "forgetting" to check glucose and says, "It's not that serious." What is the client most likely using?
Correct answer: C
Minimizing a serious diagnosis is a form of denial, often an early response to bad news. The nurse explores feelings and gives information at a pace the client can handle.
Source: Varcarolis' Foundations of Psychiatric-Mental Health Nursing, 10th ed.
Before drawing an arterial blood gas from the radial artery, what should the nurse check?
Correct answer: D
The Allen test (or a modified version) assesses ulnar artery flow to the hand in case the radial artery is damaged. Its value is debated, but it remains common practice.
Source: Lewis's Medical-Surgical Nursing, 13th ed. (arterial blood gas sampling)
A client on a continuous heparin infusion has an aPTT of 62 seconds. The control is 30 seconds, and the protocol target is 1.5 to 2.5 times control. How should the nurse interpret this?
Correct answer: B
1.5 to 2.5 times a 30-second control is 45 to 75 seconds. 62 seconds is therapeutic. Many facilities now use anti-Xa levels instead, following their protocol.
Source: Lehne's Pharmacology for Nursing Care, 12th ed. (heparin monitoring)
Yes, for the common ones. Many items expect you to recognize an abnormal electrolyte, blood count, coagulation, or blood gas result without being given the range. Next Generation NCLEX case studies often show reference ranges in the chart; when a range is given, use it.
Reference ranges vary by laboratory, testing method, and textbook. The differences are usually small. Learn one set of ranges well and focus on recognizing which direction a result is abnormal and what that means for the client.
Potassium, sodium, glucose, hemoglobin, platelets, WBC, INR and aPTT, creatinine, arterial blood gases, and therapeutic drug levels such as digoxin and lithium.
Sources: Pagana KD, Pagana TJ, Pagana TN. Mosby's Manual of Diagnostic and Laboratory Tests; MedlinePlus Medical Tests (U.S. National Library of Medicine); American Diabetes Association Standards of Care in Diabetes (A1C and glucose); Fourth Universal Definition of Myocardial Infarction (troponin). For educational use only, not medical advice.
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