NCLEX Lab Values Cheat Sheet 2026 (Must-Memorize Normal Values)

Lab values appear throughout the NCLEX-RN, especially in the Reduction of Risk Potential and Physiological Adaptation categories. You must memorize the normal ranges because the NCLEX expects you to recognize abnormal values and respond appropriately.

This cheat sheet contains every lab value you need for the 2026 NCLEX-RN, organized by category with nursing implications.

Electrolytes (Highest Priority - Memorize First)

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Key Nursing Implications

Potassium is the most critical electrolyte for the NCLEX:

• Hyperkalemia (>5.0): peaked T waves, widened QRS, risk of cardiac arrest
• Hypokalemia (<3.5): flat T waves, U waves, muscle weakness, dysrhythmias
• IV potassium must NEVER be given as IV push (causes fatal cardiac arrest)

Sodium affects neurological status:

• Hyponatremia: confusion, seizures, correct slowly
• Hypernatremia: thirst, dry membranes, seizures

Calcium affects neuromuscular excitability:

• Hypocalcemia: tetany, Chvostek's and Trousseau's signs
• Hypercalcemia: weakness, kidney stones, constipation

Complete Blood Count (CBC)

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Key Nursing Implications

WBC:

• Elevated (leukocytosis): infection, inflammation, leukemia
• Low (leukopenia): immunosuppression, risk of infection
• Neutropenia (ANC <500): severe infection risk, neutropenic precautions

Hemoglobin/Hematocrit:

• Low: anemia, bleeding (transfuse if <7 g/dL or symptomatic)
• Hct is roughly 3 times the Hgb

Platelets:

• <50,000: bleeding precautions
• <20,000: spontaneous bleeding risk
• HIT (heparin-induced thrombocytopenia): sudden drop while on heparin

Arterial Blood Gases (ABG)

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ABG Interpretation (ROME Method)

Respiratory Opposite: pH and CO2 move in opposite directions

Metabolic Equal: pH and HCO3 move in same direction

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Steps to interpret:

• Look at pH (acidotic <7.35 or alkalotic >7.45)
• Look at CO2 (respiratory indicator)
• Look at HCO3 (metabolic indicator)
• Match which one (CO2 or HCO3) explains the pH
• Check for compensation

Kidney Function

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Key Nursing Implications

• Elevated BUN and creatinine: kidney impairment
• BUN can also rise with dehydration, GI bleeding
• Creatinine is more specific to kidney function
• Hold metformin and nephrotoxic drugs if creatinine elevated
• GFR <60 for 3+ months indicates chronic kidney disease

Coagulation Studies

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Key Nursing Implications

Warfarin monitored by INR:

• Therapeutic: 2.0-3.0 (most conditions)
• INR >4-5: high bleeding risk, hold warfarin, give vitamin K

Heparin monitored by aPTT:

• Therapeutic: 1.5-2.5 times control
• Too high: bleeding risk, antidote is protamine sulfate

Glucose

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Key Nursing Implications

• Hypoglycemia (<70): give 15g fast carbs, recheck in 15 min
• Hyperglycemia (>250 with ketones): possible DKA
• A1C reflects 2-3 month average glucose
• Hold insulin if hypoglycemic

Cardiac Markers

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Key Nursing Implications

• Troponin: most specific cardiac marker, rises 3-4 hours after MI, stays elevated 7-14 days
• BNP: indicates heart failure severity (>400 significant)

Therapeutic Drug Levels

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Key Nursing Implications

Digoxin toxicity: nausea, vomiting, visual changes (yellow halos), dysrhythmias. Check potassium (hypokalemia increases toxicity).

Lithium toxicity: tremor, ataxia, confusion. Maintain consistent sodium/fluid intake.

Most Tested Lab Values on the NCLEX

If you have limited time, prioritize memorizing these:

• Potassium (3.5-5.0) - most tested
• Sodium (135-145)
• ABG values (pH 7.35-7.45, CO2 35-45, HCO3 22-26)
• Hemoglobin (12-18)
• Platelets (150,000-400,000)
• INR (therapeutic 2-3)
• Glucose (70-110 fasting)
• Creatinine (0.6-1.3)
• Digoxin (0.5-2.0)
• WBC (4,500-11,000)

Frequently Asked Questions

Do I need to memorize all lab values?

Focus on the high-yield ones (electrolytes, CBC, ABG, coagulation, glucose, common drug levels). The NCLEX rarely tests obscure values.

Will the NCLEX give me normal ranges?

No. You must know them. The NCLEX expects you to recognize abnormal values without reference.

Which lab value is most important for the NCLEX?

Potassium. It appears frequently and has life-threatening implications (cardiac arrest) at abnormal levels.

Practice Lab Value Questions at LisensyaPrep

LisensyaPrep's NCLEX quiz includes lab value interpretation in Module 5 (Reduction of Risk Potential) and throughout other modules.

Start Free NCLEX Practice at LisensyaPrep

Related NCLEX Articles

• Physiological Adaptation Reviewer for NCLEX-RN
• Pharmacology Reviewer for NCLEX-RN
• How to Pass the NCLEX on Your First Take
• NCLEX 2026 Coverage and Test Plan Changes
• Management of Care Reviewer for NCLEX-RN