You do not need every number — you need the pattern that changes what you will do next. This cheat sheet distills the CBC and CMP into quick tables, fast interpretation cues, and nurse-priority actions. Use it before clinical, during practice questions, or when an NGN case stem throws multiple labs at you at once.
For a broader list of ranges, keep the Lab Values Cheat Sheet open while you read. For acid–base questions tied to CMP bicarbonate, pair this with the ABG Interpretation guide.
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Table of Contents
- How to Use This Cheat Sheet
- CBC: Quick Ranges and What They Mean
- CBC Interpretation Patterns
- CMP: Quick Ranges and What They Mean
- CMP Interpretation Patterns
- When to Worry: Red Flags and First Actions
- NGN Tie-Ins: Action and Parameter Pairs
- NCLEX Practice Questions
- FAQ
- Further Reading
How to Use This Cheat Sheet
Scan ranges to refresh anchors, but think in patterns — not isolated numbers.
- Name the single priority in one sentence.
- Choose two actions that change physiology.
- Pick two parameters you will reassess soon (10–30 minutes when appropriate) to prove the actions worked.
Note: Ranges vary by lab, assay, and population. Always compare with your facility’s or course’s reference ranges.
CBC: Quick Ranges and What They Mean
| Test | Typical Adult Range | What It Tells You |
|---|---|---|
| WBC | 4.0–11.0 ×10³/μL | Inflammation/infection; trend and differential matter |
| Hemoglobin (Hgb) | F: 12–16 g/dL; M: 13.5–17.5 g/dL | Oxygen-carrying capacity; bleeding vs dehydration |
| Hematocrit (Hct) | F: 36–46%; M: 41–53% | Proportion of RBCs; tracks with Hgb |
| RBC Count | F: 3.8–5.2; M: 4.3–5.7 ×10⁶/μL | Quantity of red cells (interpret with indices) |
| MCV | 80–100 fL | Cell size: microcytic vs macrocytic anemia |
| MCHC | 32–36 g/dL | Hemoglobin concentration per RBC |
| RDW | 11–15% | Variation in RBC size; mixed deficiencies |
| Platelets | 150–400 ×10³/μL | Clotting; low increases bleeding risk |
Leukocyte differential (fast cues): Neutrophils ↑ (left shift) = likely bacterial infection. Lymphocytes ↑ = often viral or chronic immune stimulation. Eosinophils ↑ = allergy, asthma, parasites. Bands ↑ = acute infection or severe stressor.
CBC Interpretation Patterns
Anemia pattern: ↓Hgb/↓Hct → assess for bleeding, nutrition, chronic disease. Microcytic (low MCV): iron deficiency, chronic blood loss. Macrocytic (high MCV): B12/folate deficiency, alcohol, some medications. First actions: trend vitals, assess bleeding signs, consider stool/menstrual history.
Hemoconcentration: ↑Hgb/↑Hct with dehydration signs → fluids as ordered; reassess MAP and urine output.
Leukocytosis with left shift: Suspect bacterial infection. Check temp, identify source, obtain cultures per protocol. If accompanied by hypotension and tachycardia, consider sepsis — see Types of Shock NCLEX Review for septic shock management.
Neutropenia: Infection risk. Institute protective precautions. Monitor for subtle sepsis signs (the patient may not mount a fever).
Thrombocytopenia: Bleeding risk. Review medications (heparin — consider HIT). Assess for petechiae, hematuria, melena. Avoid IM injections as appropriate. For anticoagulant monitoring, see the Lab Values Cheat Sheet coagulation section.
CMP: Quick Ranges and What They Mean
| Test | Typical Adult Range | What It Tells You |
|---|---|---|
| Sodium (Na¹) | 135–145 mEq/L | Water balance, neurologic status |
| Potassium (K¹) | 3.5–5.0 mEq/L | Cardiac conduction, muscle function |
| Chloride (Cl¯) | 96–106 mEq/L | Acid–base partner to bicarbonate |
| CO&sub2; (HCO&sub3;¯) | 22–29 mEq/L | Metabolic component of acid–base |
| BUN | 7–20 mg/dL | Hydration/renal perfusion |
| Creatinine | ~0.6–1.3 mg/dL | Renal filtration; compare to baseline/eGFR |
| Glucose (fasting) | 70–99 mg/dL | Metabolic control; context: therapy, steroids, sepsis |
| Calcium (total) | 8.6–10.2 mg/dL | Neuromuscular tone; correct for albumin |
| Albumin | 3.5–5.0 g/dL | Oncotic pressure; chronic nutrition/liver status |
| ALP | ~40–129 U/L | Cholestasis, bone turnover |
| AST | ~10–40 U/L | Hepatocellular injury (also muscle) |
| ALT | ~7–56 U/L | More liver-specific than AST |
| Total Bilirubin | ~0.2–1.2 mg/dL | Hemolysis/cholestasis; jaundice patterns |
Helpful formulas: Corrected Ca²¹ (mg/dL) ≈ measured Ca²¹ + 0.8 × (4.0 − albumin). Anion Gap ≈ Na¹ − (Cl¯ + HCO&sub3;¯). Elevated gap → MUDPILES patterns (DKA, lactic acidosis, toxins).
CMP Interpretation Patterns
Sodium
HypoNa¹ with confusion/seizure: Treat safely per protocol. Avoid rapid correction (risk of osmotic demyelination). Neuro checks frequently.
HyperNa¹ with dehydration: Fluid replacement guided by volume status. Monitor mental status and sodium trend.
Potassium
HyperK¹ (≥6.0 or ECG changes): Stabilize myocardium (calcium per protocol), shift K¹ intracellularly (insulin + dextrose, β-agonist), remove K¹ (diuretics/resins/dialysis). Continuous ECG; recheck K¹. For ECG changes with potassium abnormalities, see the Heart Rhythm Strips Cheat Sheet.
HypoK¹: Replace and monitor. Evaluate Mg²¹ (low Mg makes K¹ repletion harder). For diuretic-induced hypokalemia, see the Pharmacology Mnemonics Cheat Sheet diuretics section.
Bicarbonate / Acid–Base
Low HCO&sub3;¯: Metabolic acidosis — think DKA, sepsis, renal failure. Pair with ABG, lactate. Treat cause; trend gap and HCO&sub3;¯.
High HCO&sub3;¯: Metabolic alkalosis — vomiting, NG suction, or diuretics. Replace Cl¯/K¹; reassess symptoms.
Renal
Azotemia (↑BUN/Cr): Pre-renal (hypoperfusion), intrinsic renal, or post-renal obstruction. Check UOP, volume status, nephrotoxic meds. Adjust doses by eGFR. Monitor MAP.
Liver (LFT Patterns)
AST/ALT >> ALP/bili: Hepatocellular injury (viral, toxins, meds, ischemic).
ALP + bili >> AST/ALT: Cholestasis/obstruction (stones, tumor). Evaluate RUQ pain, pruritus.
Low albumin (chronic): Nutrition or liver synthesis issue. Influences corrected calcium and drug binding.
When to Worry: Red Flags and First Actions
WBC >12k with fever or hypotension: Consider sepsis. Follow local sepsis bundle. Reassess MAP, urine output, lactate. See Types of Shock NCLEX Review for septic shock protocol.
Hgb falling with hypotension, pallor, melena: Suspect active bleed. Large-bore IVs, fluids, type and screen. Monitor MAP/UOP.
Platelets <100k with heparin exposure + new clot: Think HIT. Stop heparin immediately. Alternative anticoagulation per order. For heparin vs warfarin monitoring, see the Lab Values Cheat Sheet coagulation section.
Na¹ acute drop with confusion/seizure: Treat safely per protocol. Avoid rapid overcorrection. Frequent neuro checks.
K¹ ≥6.0 or ECG changes: Stabilize myocardium, shift K¹ intracellularly, remove K¹. Continuous cardiac monitoring.
Cr rising fast with low UOP: Review meds, hydrate per order, trend output. Prevent further nephrotoxic exposures.
ALT/AST into the hundreds/thousands: Notify provider, trend LFTs, evaluate for obstruction/injury. Monitor mental status and coags if severe.
NGN Tie-Ins: Action and Parameter Pairs
Link every action to the parameter that should budge first. This is the core skill NGN case studies test. For full NGN practice, see NGN Case Studies (2026): 25 Free Examples.
DKA (CMP: low HCO&sub3;¯, high glucose, K¹ shifts): Actions: fluids then insulin. Parameters: anion gap, glucose, potassium.
COPD exacerbation (CMP near-normal; ABG abnormal): Actions: oxygen to target sats, bronchodilator. Parameters: SpO&sub2;/WOB, PaCO&sub2;.
Acute bleed (CBC changes may lag early): Actions: IV access, fluids/blood per order. Parameters: MAP, UOP, mentation.
Cholestasis pattern (ALP + bilirubin): Actions: assess for obstruction, symptom control. Parameters: bilirubin/ALP trend, pruritus relief.
Renal perfusion problem (↑BUN/Cr, low UOP): Actions: fluids if pre-renal, review nephrotoxins. Parameters: UOP, Cr/eGFR, MAP.
NCLEX Practice Questions
Question 1. A client’s CBC results show: WBC 14.2, Hgb 8.1, Hct 24%, Platelets 210. The client has dark tarry stools and HR 112. What is the priority nursing action?
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Question 2. A client’s CMP shows: K¹ 6.3 mEq/L, Na¹ 138, BUN 32, Cr 2.8. ECG shows peaked T waves. Which intervention should the nurse anticipate first?
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Question 3. A client on day 2 of TPN has a CMP showing glucose 284 mg/dL, Na¹ 141, K¹ 3.2, albumin 2.1. Which lab finding requires the most urgent intervention?
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FAQ
Do I need to memorize every range? Know the anchors and patterns. Use this cheat sheet for ranges, then focus on what changes first and how you will measure it.
CBC looks normal but the client is unstable — what now? Trends and the clinical picture come first. In active bleeding, vitals and assessment often lead labs. Treat the priority, then trend labs.
CMP bicarbonate is low — do I always have metabolic acidosis? Often yes, but confirm with ABG and the clinical story. Treat the cause (DKA, sepsis) and track the gap and HCO&sub3;¯.
How fast should I see improvements? Some parameters move quickly (SpO&sub2;, MAP, RR); others lag (Hgb/Hct after fluids, albumin). Pick parameters that show near-term change.
Further Reading
- Lab Values Cheat Sheet for Nursing Students (2026) — the complete lab reference with ranges for CBC, BMP, CMP, coags, ABG, and cardiac markers
- Heart Rhythm Strips Cheat Sheet (2026) — ECG changes from electrolyte abnormalities
- Pharmacology Mnemonics Cheat Sheet (2026) — drug mnemonics for medications that affect labs (diuretics, ACE inhibitors, anticoagulants)
- Types of Shock NCLEX Review (2026) — lab-guided shock management
- NGN Case Studies (2026): 25 Free Examples with Answers
- Mastering SATA Questions (2026)
- 2026 NCLEX Changes Hub
- Free NCLEX Practice Quizzes
