Normal Adult Lab Values

What is the normal sodium ($\text{Na}^+$) range?

$$136\text{--}145\,\text{mEq/L}$$

What is the normal serum potassium ($\text{K}^+$) range?

$$3.5\text{--}5.2\,\text{mEq/L}$$

What is the normal ionized calcium ($\text{Ca}^{2+}$) range?

$$4.65\text{--}5.28\,\text{mg/dL}$$

What is the normal total serum calcium range?

$$8.8\text{--}10.4\,\text{mg/dL}$$

What is the normal serum chloride ($\text{Cl}^-$) range?

$$96\text{--}106\,\text{mEq/L}$$

What is the normal magnesium ($\text{Mg}^{2+}$) range?

$1.8\text{--}2.6\,\text{mg/dL}$ (Note: Magnesium may be slightly lower during the second and third trimesters of pregnancy.)

What is the normal phosphate/phosphorus range?

$$2.7\text{--}4.5\,\text{mg/dL}$$

What is the normal Blood Urea Nitrogen (BUN) level for adults?

$$6\text{--}20\,\text{mg/dL}$$

What is the normal Blood Urea Nitrogen (BUN) level for adults over age 60?

$$8\text{--}23\,\text{mg/dL}$$

What is the normal serum creatinine range for males?

$$0.6\text{--}1.3\,\text{mg/dL}$$

What is the normal serum creatinine range for females?

$$0.6\text{--}1.1\,\text{mg/dL}$$

What is the normal AST range for males? aspartate aminotransferase

$$14\text{--}20\,\text{units/L}$$

What is the normal AST range for females?

$$10\text{--}36\,\text{units/L}$$

What is the normal ALT range for males?

$$10\text{--}40\,\text{units/L}$$

What is the normal ALT range for females? (alanine aminotransferase)

$$7\text{--}35\,\text{units/L}$$

What is the normal albumin range?

$$3.5\text{--}5.2\,\text{g/dL}$$

What is the normal prealbumin range?

$$19\text{--}38\,\text{mg/dL}$$

What is the normal serum $\text{CO}_2$ range?

$$23\text{--}30\,\text{mEq/L}$$

What is the normal anion gap?

$$8\text{--}16\,\text{mEq/L}$$

What is the normal serum osmolality range?

$$275\text{--}295\,\text{mOsm/kg H}_2\text{O}$$

What is the normal fasting blood glucose level for adults?

$\le 100\,\text{mg/dL}$ (SI value: $\le 5.6\,\text{mmol/L}$)

What is the normal hemoglobin A1c (HbA1c) level?

$$\le 5.6\%$$

What is the normal arterial blood pH range?

$$7.35\text{--}7.45$$

What is the normal $\text{PaCO}_2$ range?

$$35\text{--}45\,\text{mm Hg}$$

What is the normal $\text{HCO}_3^-$ range?

$$22\text{--}32\,\text{mEq/L}$$

What is the normal $\text{PaO}_2$ level?

$$>80\,\text{mm Hg}$$

What is the normal $\text{SaO}_2$ level? (arterial oxygen saturation)

$$>94\%$$

What is the normal white blood cell (WBC) count?

$4.5\text{--}10.5 \times 10^3\,\text{cells/mm}^3$ or $4.5\text{--}10.5 \times 10^9/\text{L}$

What is the normal RBC count for males?

$$4.2\text{--}5.4 \times 10^6/\text{mm}^3$$

What is the normal RBC count for females?

$$3.6\text{--}5.0 \times 10^6/\text{mm}^3$$

What is the normal hemoglobin (Hgb) range for males?

$$14\text{--}17.4\,\text{g/dL}$$

What is the normal hemoglobin (Hgb) range for females?

$$12\text{--}16\,\text{g/dL}$$

What is the normal hematocrit (Hct) range for males?

$$42\%\text{--}52\%$$

What is the normal hematocrit (Hct) range for females?

$$36\%\text{--}48\%$$

What is the normal platelet count?

$$140,000\text{--}400,000/\text{mm}^3$$

What is the normal prothrombin time (PT)?

$$11\text{--}13\,\text{seconds}$$

What is the normal INR for a patient not taking an anticoagulant?

$$0.8\text{--}1.2$$

What is the therapeutic INR range for a patient taking warfarin?

$$2.0\text{--}3.0$$

What is the INR range for a patient with a mechanical prosthetic heart valve?

$$2.5\text{--}3.5$$

What is the normal APTT range? (Activated Partial Thromboplastin Time)

$$21\text{--}35\,\text{seconds}$$

What is the normal total cholesterol range?

$$140\text{--}199\,\text{mg/dL}$$

What is the normal HDL range for males?

$$35\text{--}65\,\text{mg/dL}$$

What is the normal HDL range for females?

$$35\text{--}80\,\text{mg/dL}$$

What is the normal LDL-C level? (Low-density lipoprotein)

$$<100\,\text{mg/dL}$$

What is the normal LDL-P level?

$$<1,000\,\text{nmol/L}$$

What is the normal triglyceride level?

$$<150\,\text{mg/dL}$$

What is the normal Triiodothyronine level (T3) range for adults?

$$80\text{--}200\,\text{ng/dL}$$

During pregnancy: 116 to 247 ng/dL

What is the normal T3 range during pregnancy?

$116\text{--}247\,\text{ng/dL}$ (SI value: $1.8\text{--}3.8\,\text{nmol/L}$)

What is the normal T4 (Thyroxine) level range?

$$5.4\text{--}11.5\,\mu\text{g/dL}$$

What is the normal TSH range? (Thyroid-stimulating hormone  )

$0.45\text{--}4.5\,\mu\text{U/mL}$ (SI value: $0.45\text{--}4.5\,\text{mU/L}$)

What are the nurse’s responsibilities when collecting laboratory specimens?

Verify the order, identify the patient using two identifiers, explain the procedure, check preparation requirements, use appropriate precautions, collect and label the specimen correctly, transport promptly, document, and report abnormal findings.

What should the nurse do when a laboratory result is critically abnormal?

Assess the patient for related symptoms, promptly notify the provider or activate emergency response if unstable, implement appropriate interventions/orders, and reassess.

What does a complete blood count (CBC) measure, and why is it ordered?

Measures RBCs, hemoglobin, hematocrit, WBCs, and platelets. Helps identify anemia, infection, inflammation, and bleeding disorders.

What are the functions of RBCs, hemoglobin, and hematocrit, and what do abnormal results indicate?

RBCs transport oxygen; hemoglobin carries oxygen; hematocrit measures the percentage of blood made up of RBCs. Low levels may indicate anemia or blood loss, causing fatigue, pallor, and weakness. High levels may occur with dehydration or excess RBC production.

What are the functions of WBCs and platelets, and what do abnormal results indicate?

WBCs fight infection; high levels may indicate infection/inflammation, while low levels increase infection risk. Platelets help blood clot; low levels increase bleeding risk, while significantly elevated levels may increase clotting risk.

What do BUN and creatinine measure, and what do elevated levels suggest?

BUN measures urea waste from protein metabolism; creatinine measures waste from muscle metabolism. Both help evaluate kidney function. High BUN may indicate dehydration or kidney dysfunction; elevated creatinine suggests impaired kidney filtration.

What do AST and ALT measure, and what do elevated levels indicate?

AST and ALT are enzymes associated with liver-cell injury. Elevated levels may indicate liver inflammation, hepatitis, medication-related toxicity, or other liver damage.

What are albumin and prealbumin, and why are they important?

Proteins produced by the liver that are affected by nutrition, inflammation, and illness. Low albumin can contribute to edema and may occur with liver disease, kidney protein loss, or inflammation. Neither test alone diagnoses malnutrition.

What are PT and INR, and what are the nursing implications of abnormal results?

They evaluate blood clotting and are used to monitor warfarin therapy. Prolonged results increase concern for bleeding. Assess for bruising, bleeding gums, bloody stools, and other bleeding signs; report significant abnormalities.

What are PTT and aPTT, and what are the nursing implications of abnormal results?

They evaluate clotting through the intrinsic and common pathways and are often used to monitor unfractionated heparin. Prolonged results may indicate increased bleeding risk. Assess for bleeding and report abnormal results.

What does total cholesterol measure, and why are elevated levels concerning?

Measures cholesterol in the blood. Elevated cholesterol may contribute to plaque buildup in arteries (atherosclerosis), increasing cardiovascular risk, including heart attack and stroke.

What are glucose and hemoglobin A1C used to evaluate, and what do abnormal results indicate?

Glucose measures current blood sugar; A1C reflects average glucose over about 2–3 months. Low glucose may cause sweating, shakiness, and confusion. High glucose may cause thirst, frequent urination, and poor wound healing. Elevated A1C suggests prolonged hyperglycemia.

What is potassium’s role, and what happens when it is too high or too low?

Potassium supports nerve impulses, muscle contraction, and heart rhythm. Low potassium may cause weakness, cramps, and dysrhythmias. High potassium may cause weakness and life-threatening cardiac dysrhythmias. Cardiac assessment is a priority.

What is sodium’s role, and what happens when it is too high or too low?

Sodium regulates fluid balance and nerve function. Low sodium can cause headache, confusion, weakness, or seizures. High sodium can cause thirst, irritability, confusion, and neurologic complications.

What is calcium’s role, and what happens when it is too high or too low?

Calcium supports bones, muscle contraction, nerve transmission, and clotting. Low calcium may cause tingling, muscle spasms, and tetany. High calcium may cause weakness, constipation, kidney stones, and confusion.

What is chloride’s role, and what do abnormal results indicate?

Chloride helps maintain fluid balance and acid–base balance. Abnormal levels may occur with dehydration, vomiting, kidney problems, or acid–base disturbances.

What is magnesium’s role, and what happens when it is too high or too low?

Magnesium supports nerve, muscle, and cardiac function. Low magnesium may cause tremors, increased reflexes, seizures, and dysrhythmias. High magnesium may cause decreased reflexes, weakness, hypotension, and respiratory depression.

What is phosphorus/phosphate’s role, and what happens when it is abnormal?

Phosphorus supports bone health, cellular energy (ATP), and muscle function. Low levels may cause weakness and impaired respiratory muscle function. High levels may occur with kidney dysfunction and contribute to low calcium.

What does each ABG component measure?

pH measures blood acidity/alkalinity; PaCO2 reflects ventilation and the respiratory component; HCO3 reflects the metabolic component; PaO2 measures oxygen dissolved in arterial blood; SaO2 measures the percentage of hemoglobin saturated with oxygen. Know their normal values from your existing flashcards.

What is therapeutic drug monitoring, and what are the nurse’s responsibilities?

Measures medication concentrations in the blood to ensure effectiveness and prevent toxicity. Verify correct specimen timing, last dose, kidney function, and adverse effects. Some drugs require peak or trough monitoring, such as gentamicin; vancomycin monitoring may use AUC-based methods.

What are the nursing responsibilities and patient teaching for urine and stool studies?

Explain collection, prevent contamination, use the correct container, and transport promptly. Clean-catch urine requires appropriate cleansing and midstream collection. Stool specimens must not mix with urine or toilet water. Follow ordered dietary or medication restrictions for specific tests.

What are culture and sensitivity tests, and what nursing responsibilities are important?

Cultures identify microorganisms causing infection; sensitivity testing determines which antibiotics may work. Collect specimens before antibiotics when feasible without delaying urgent treatment, maintain proper collection technique, label correctly, and transport promptly.

What is an X-ray, and what nursing care is required before and after?

Uses ionizing radiation to examine bones and internal structures. Before: assess pregnancy possibility when relevant, remove interfering metal, and assist with positioning. After: routine plain X-rays usually require no special care; follow additional precautions for contrast studies.

What is fluoroscopy, and what nursing care is required?

Uses continuous or pulsed X-rays to produce real-time moving images, often with contrast. Before: verify preparation, possible fasting, pregnancy status, and contrast precautions. After: monitor for contrast reactions and procedure-specific complications.

What is endoscopy, and what are the priority nursing responsibilities before and after?

Uses a flexible scope to visualize internal organs and sometimes obtain biopsies. Before: verify consent, fasting or bowel preparation, allergies, and sedation requirements. After: monitor airway, breathing, vital signs, bleeding, and perforation symptoms. After upper GI endoscopy, verify gag/swallow reflex before oral intake.

What is ultrasonography (ultrasound), and what nursing preparation is needed?

Uses sound waves to visualize organs, tissues, and blood flow without ionizing radiation. Preparation varies: pelvic ultrasound may require a full bladder; abdominal ultrasound may require fasting. Usually minimal postprocedure care.

What is a CT scan, and what are the nursing priorities before and after?

Uses X-rays to create detailed cross-sectional images. Before: assess pregnancy possibility, contrast reaction history, kidney function when indicated, IV access, and preparation requirements. After IV contrast: monitor for reactions and encourage hydration when appropriate.

What is an MRI, and what are the priority nursing safety considerations?

Uses strong magnetic fields and radio waves to produce detailed images without ionizing radiation. Screen for pacemakers, implants, metallic foreign bodies, and unsafe equipment; remove metal and assess claustrophobia. If gadolinium contrast is planned, assess kidney function when indicated.

What is a nuclear scan, and what nursing care is required?

Uses a small amount of radioactive tracer to assess organ function. Before: assess pregnancy or breastfeeding considerations, explain tracer administration and required waiting time. After: follow tracer-specific hydration, voiding, and radiation-safety instructions.

How does the Clinical Judgment Model apply to abnormal labs and diagnostic findings?

Recognize cues (identify abnormal findings), analyze cues (interpret meaning), prioritize hypotheses (identify the most urgent problem), generate solutions (plan care), take action (implement interventions), and evaluate outcomes (reassess). Example: elevated potassium with ECG changes requires urgent escalation due to cardiac dysrhythmia risk.