Free Reference
Normal Lab Values for Nurses (NCLEX Reference)
A clean, printable reference of the normal lab values every nursing student must memorize for the NCLEX, HESI, and clinicals – 42 labs across 9 categories, each with a quick clinical pearl. Then test yourself with the free lab-value quiz below.
| Lab | Normal range | Clinical note |
|---|---|---|
| Sodium (Na+) | 135 to 145 mEq/L | Hyponatremia (less than 135) causes confusion and seizures; hypernatremia (greater than 145) causes thirst and neurologic changes. |
| Potassium (K+) | 3.5 to 5.0 mEq/L | Critical to cardiac conduction; both hypokalemia and hyperkalemia can cause life-threatening dysrhythmias. |
| Chloride (Cl-) | 98 to 106 mEq/L | Often changes inversely with bicarbonate; low chloride is seen with vomiting and metabolic alkalosis. |
| Calcium (Ca2+) | 8.5 to 10.5 mg/dL | Hypocalcemia causes tetany and positive Trousseau sign; hypercalcemia causes 'bones, stones, groans, and moans'. |
| Magnesium (Mg2+) | 1.5 to 2.5 mEq/L | Hypomagnesemia often accompanies hypokalemia and hyponatremia; low levels can trigger ventricular dysrhythmias. |
| Phosphorus (PO4) | 2.5 to 4.5 mg/dL | Inversely related to calcium; hyperphosphatemia is common in chronic kidney disease and can cause hypocalcemia. |
| Lab | Normal range | Clinical note |
|---|---|---|
| Hemoglobin (Hgb) | 12 to 17 g/dL | Values below 7 g/dL often prompt transfusion consideration; low Hgb is the hallmark of anemia. |
| Hematocrit (Hct) | 37 to 52 percent | Approximately three times the hemoglobin value; elevated in dehydration, decreased in bleeding or anemia. |
| White Blood Cell Count (WBC) | 4,500 to 11,000 cells/mcL | Leukocytosis (greater than 11,000) suggests infection or inflammation; leukopenia (less than 4,500) increases infection risk. |
| Platelets (PLT) | 150,000 to 400,000 cells/mcL | Thrombocytopenia (less than 150,000) increases bleeding risk; counts less than 50,000 require precautions; less than 20,000 is critical. |
| Red Blood Cell Count (RBC) | 4.2 to 5.9 million cells/mcL | Decreased in anemia, blood loss, and bone marrow suppression; elevated in polycythemia vera and chronic hypoxia. |
| Lab | Normal range | Clinical note |
|---|---|---|
| Blood Urea Nitrogen (BUN) | 7 to 20 mg/dL | Elevated BUN indicates impaired renal function, dehydration, or high protein intake; used with creatinine in the BUN-to-creatinine ratio. |
| Creatinine (Cr) | 0.6 to 1.2 mg/dL | More specific indicator of kidney function than BUN; elevated creatinine indicates decreased glomerular filtration rate. |
| Glomerular Filtration Rate (GFR) | Greater than 60 mL/min/1.73 m2 | Less than 60 for three or more months indicates chronic kidney disease; less than 15 indicates kidney failure requiring dialysis. |
| Uric Acid | 3.5 to 7.2 mg/dL | Elevated uric acid (hyperuricemia) is associated with gout and can cause urate crystal deposits in joints and kidneys. |
| Lab | Normal range | Clinical note |
|---|---|---|
| Alanine Aminotransferase (ALT) | 7 to 56 units/L | Most specific marker for hepatocellular damage; markedly elevated in viral hepatitis and drug-induced liver injury. |
| Aspartate Aminotransferase (AST) | 10 to 40 units/L | Elevated in liver disease and myocardial infarction; less liver-specific than ALT but used together to assess liver damage. |
| Total Bilirubin | 0.2 to 1.2 mg/dL | Elevated bilirubin causes jaundice; direct (conjugated) elevation suggests obstruction, indirect (unconjugated) elevation suggests hemolysis. |
| Albumin | 3.5 to 5.0 g/dL | Low albumin reflects poor nutritional status or chronic liver disease; affects drug binding and osmotic pressure. |
| Alkaline Phosphatase (ALP) | 44 to 147 units/L | Elevated in liver disease, bone disorders, and biliary obstruction; must interpret alongside other liver function tests. |
| Lab | Normal range | Clinical note |
|---|---|---|
| pH | 7.35 to 7.45 | Less than 7.35 is acidosis; greater than 7.45 is alkalosis. Values less than 7.2 or greater than 7.6 are life-threatening. |
| PaCO2 (Partial Pressure of Carbon Dioxide) | 35 to 45 mmHg | Respiratory acid-base regulator; elevated PaCO2 causes respiratory acidosis, decreased PaCO2 causes respiratory alkalosis. |
| PaO2 (Partial Pressure of Oxygen) | 80 to 100 mmHg | Values less than 60 mmHg indicate hypoxemia requiring supplemental oxygen; decreases with age and altitude. |
| Bicarbonate (HCO3-) | 22 to 26 mEq/L | Metabolic acid-base regulator; less than 22 indicates metabolic acidosis, greater than 26 indicates metabolic alkalosis. |
| SaO2 (Oxygen Saturation) | 95 to 100 percent | Less than 90 percent indicates significant hypoxemia; pulse oximetry (SpO2) is the noninvasive correlate. |
| Lab | Normal range | Clinical note |
|---|---|---|
| Prothrombin Time (PT) | 11 to 13.5 seconds | Monitors extrinsic clotting pathway and warfarin therapy; prolonged PT indicates risk of bleeding. |
| International Normalized Ratio (INR) | 0.8 to 1.2 (therapeutic for anticoagulation: 2.0 to 3.0) | Standardized measure of PT; INR greater than 3.0 in non-anticoagulated patients signals serious bleeding risk. |
| Activated Partial Thromboplastin Time (aPTT) | 25 to 35 seconds | Monitors intrinsic pathway and heparin therapy; therapeutic aPTT for heparin is 1.5 to 2.5 times the normal value. |
| D-Dimer | Less than 0.50 mcg/mL (500 ng/mL) | Elevated in deep vein thrombosis, pulmonary embolism, and DIC; useful as a rule-out test when negative. |
| Lab | Normal range | Clinical note |
|---|---|---|
| Troponin I | Less than 0.04 ng/mL | Rises within 3 to 6 hours of myocardial injury and remains elevated for 7 to 10 days; most sensitive and specific marker for MI. |
| Creatine Kinase-MB (CK-MB) | Less than 3 percent of total CK (or less than 5 ng/mL) | Rises 4 to 6 hours after MI and returns to normal within 48 to 72 hours; useful for detecting reinfarction. |
| B-type Natriuretic Peptide (BNP) | Less than 100 pg/mL | Elevated BNP indicates ventricular wall stress; used to diagnose and monitor heart failure severity. |
| Lab | Normal range | Clinical note |
|---|---|---|
| Fasting Blood Glucose | 70 to 99 mg/dL | Less than 70 mg/dL is hypoglycemia; 100 to 125 mg/dL is prediabetes; greater than or equal to 126 mg/dL indicates diabetes. |
| Hemoglobin A1c (HbA1c) | Less than 5.7 percent (diabetic goal: less than 7.0 percent) | Reflects average blood glucose over the past 2 to 3 months; used to diagnose and monitor diabetes management. |
| Total Cholesterol | Less than 200 mg/dL | Values of 200 to 239 mg/dL are borderline high; greater than or equal to 240 mg/dL is high and increases cardiovascular risk. |
| LDL Cholesterol | Less than 100 mg/dL (optimal) | 'Bad' cholesterol; primary target for statin therapy. Less than 70 mg/dL is recommended for high cardiovascular risk patients. |
| HDL Cholesterol | Greater than 40 mg/dL in men, greater than 50 mg/dL in women | 'Good' cholesterol; HDL greater than 60 mg/dL is cardioprotective; low HDL is an independent cardiovascular risk factor. |
| Lab | Normal range | Clinical note |
|---|---|---|
| Thyroid Stimulating Hormone (TSH) | 0.4 to 4.0 mIU/L | Elevated TSH indicates hypothyroidism; suppressed TSH indicates hyperthyroidism. Best initial screening test for thyroid function. |
| Serum Iron | 60 to 170 mcg/dL | Low serum iron with high TIBC confirms iron-deficiency anemia; high iron with low TIBC suggests hemochromatosis. |
| Serum Lactate | 0.5 to 2.0 mmol/L | Elevated lactate (greater than 2 mmol/L) indicates tissue hypoperfusion; greater than 4 mmol/L signals severe sepsis or shock. |
| C-Reactive Protein (CRP) | Less than 1.0 mg/dL (high-sensitivity CRP: less than 3.0 mg/L) | Nonspecific marker of systemic inflammation; markedly elevated in infection, autoimmune conditions, and acute MI. |
| Erythrocyte Sedimentation Rate (ESR) | 0 to 20 mm/hr in men, 0 to 30 mm/hr in women | Nonspecific inflammation marker; elevated in autoimmune diseases, infection, and malignancy. Rises more slowly than CRP. |
Test yourself: Lab Values Quiz
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