Cheat sheets
🧪

Normal Lab Values + Panic Levels

The values you're expected to know cold, with the panic thresholds and the first nursing action for each.

Free · print it · share it · no gatekeeping

Electrolytes

Sodium
135–145 · panic <120 or >160 · correct slowly — osmotic demyelination
Potassium
3.5–5.0 · panic <2.5 or >6.5 · peaked T waves → calcium, insulin+D50, albuterol
Calcium (total)
8.5–10.5 · ionized 1.1–1.3 · watch after massive transfusion
Magnesium
1.5–2.5 · low mag makes potassium unfixable
Phosphate
2.5–4.5 · low = failure to wean from the vent

Renal & metabolic

BUN
7–20 mg/dL
Creatinine
0.6–1.2 mg/dL · trend matters more than the value
Glucose
70–110 fasting · treat <70 with 15 g carbs, recheck in 15 min
Lactate
<2 mmol/L · >4 = tissue hypoperfusion, act now

Hematology & coags

Hgb
12–16 (F) / 14–18 (M) · transfuse per protocol + symptoms
Platelets
150–400 K · <50 K = bleeding risk for procedures
WBC
5–10 K · left shift = bands rising
INR
0.8–1.1 · therapeutic 2–3 on warfarin
aPTT
25–35 s · 1.5–2.5× baseline on heparin

ABGs

pH
7.35–7.45
PaCO2
35–45 mmHg · respiratory driver
HCO3
22–26 mEq/L · metabolic driver
PaO2
80–100 mmHg
Read it
ROME: Respiratory Opposite, Metabolic Equal

Baddie pearls 👑

  • A single value is a rumor. A trend is a story. Chart the trend.
  • Critical value = closed-loop read-back to the provider AND documentation of the time.
  • Ranges vary by lab — always use your facility's reference range for real decisions.

Educational reference only. Always follow your facility's current policies, protocols, and provider orders.

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