Quick Reference
Clinical Lab Values
Essential labs, reference ranges, and things to flag — organized like a bedside cheat sheet.
Electrolytes
- Potassium (K⁺)
- 3.5 – 5.0 mEq/L
- Sodium (Na⁺)
- 135 – 145 mEq/L
- Calcium, total
- 8.6 – 10.2 mg/dL
- Calcium, ionized
- 4.5 – 5.5 mg/dL
- Magnesium (Mg²⁺)
- 1.3 – 2.0 mEq/L
- Phosphorus
- 3.0 – 4.5 mg/dL
- Chloride (Cl⁻)
- 96 – 106 mEq/L
Clinical focus
- •Report K⁺ < 2.5 or > 6.0 immediately
- •Na⁺ < 120 or > 160 is critical
- •Trend with I&O and daily weights
Renal Function
- BUN
- 10 – 20 mg/dL
- Creatinine
- 0.6 – 1.3 mg/dL
- BUN / Cr ratio
- 10:1 – 20:1
- eGFR
- > 90 mL/min/1.73m²
Clinical focus
- •Downward eGFR trend = kidney dysfunction
- •Avoid nephrotoxic meds (NSAIDs, contrast)
- •Monitor I&O and daily weight
ABG (Room Air)
- pH
- 7.35 – 7.45
- PaCO₂
- 35 – 45 mmHg
- PaO₂
- 80 – 100 mmHg
- HCO₃⁻
- 22 – 26 mEq/L
- SaO₂
- 95 – 100%
Acid–Base quick guide
- pH ↓ acidosis · pH ↑ alkalosis
- PaCO₂ ↑ respiratory acidosis · ↓ respiratory alkalosis
- HCO₃⁻ ↓ metabolic acidosis · ↑ metabolic alkalosis
Hematology (CBC)
- WBC
- 4.0 – 11.0 K/µL
- RBC
- 4.2 – 6.0 M/µL
- Hemoglobin
- 12 – 18 g/dL
- Hematocrit
- 37 – 52%
- Platelets
- 150 – 400 K/µL
Clinical focus
- •Fever + ↑ WBC = infection
- •Low platelets = bleeding risk
- •Trend Hgb/Hct for anemia or blood loss
WBC Differential
- Neutrophils(50–70%)
- 3,000 – 7,000
- Lymphocytes(20–40%)
- 1,000 – 4,000
- Monocytes(2–8%)
- 200 – 800
- Eosinophils(1–4%)
- 50 – 500
- Basophils(0–1%)
- 0 – 100
Clinical focus
- •↑ Neutrophils → bacterial infection
- •↑ Lymphocytes → viral infection
- •↑ Eosinophils → allergies, parasites
Liver Function
- AST
- 10 – 40 U/L
- ALT
- 7 – 56 U/L
- Alk phosphatase
- 30 – 120 U/L
- Total bilirubin
- 0.3 – 1.0 mg/dL
- Albumin
- 3.5 – 5.5 g/dL
- Total protein
- 6.0 – 8.3 g/dL
Clinical focus
- •Assess jaundice, pruritus, RUQ pain
- •Avoid hepatotoxic drugs (acetaminophen limits)
- •Monitor mental status for encephalopathy
Coagulation
- PT
- 11 – 13.5 sec
- INR(no anticoag)
- 0.8 – 1.1
- PTT
- 25 – 35 sec
- Platelets
- 150 – 400 K/µL
Clinical focus
- •Assess for bleeding & bruising
- •Monitor anticoagulant therapy closely
- •Report critical values immediately
Lipid Panel
- Total cholesterol
- < 200 mg/dL
- HDL (good)
- > 60 mg/dL
- LDL (bad)
- < 100 mg/dL
- Triglycerides
- 35 – 150 mg/dL
Glucose
- Fasting
- 70 – 110 mg/dL
- Random
- < 140 mg/dL
- A1C
- < 5.7% normal
Clinical focus
- •Assess diet & exercise
- •Administer meds/insulin as ordered
- •Monitor for hypo/hyperglycemia signs
Vital Signs (Adult)
- Temp
- 97.0 – 99.5 °F
- Heart rate
- 60 – 100 bpm
- Blood pressure
- 90/60 – 120/80 mmHg
- Respiratory rate
- 12 – 20 /min
- SpO₂
- ≥ 94%
Critical — Report Now
- Potassium
- < 2.5 or > 6.0 mEq/L
- Sodium
- < 120 or > 160 mEq/L
- Calcium
- < 7.5 or > 12 mg/dL
- Hemoglobin
- < 7 or > 20 g/dL
- Platelets
- < 20K or > 1,000K
- pH
- < 7.25 or > 7.55
- Glucose
- < 50 or > 400 mg/dL
Abbreviations
- ABG — arterial blood gas
- CBC — complete blood count
- BMP — basic metabolic panel
- CMP — comprehensive metabolic
- I&O — intake & output
- LOC — level of consciousness
- PRN — as needed
- WNL — within normal limits
Always correlate labs with the whole clinical picture. If it doesn't look right, speak up.