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Essential Lab Values for Nursing

Aug 14, 2025

Overview

This lecture reviews essential lab values for nursing, explaining their meanings, normal ranges, clinical significance, and highlighting high-yield facts for NCLEX and nursing exams.

Basic Metabolic Panel (BMP) & Electrolytes

  • BMP screens sodium (Na: 135-145), potassium (K: 3.5-5.0), chloride, COâ‚‚, bicarb (HCO₃), BUN (10-20), creatinine (<1.3), and glucose (70-115).
  • Sodium swells the body; low causes mental status changes, seizures, high causes edema, red skin.
  • Potassium "pumps" muscles, especially the heart; high (K>5.0) = peaked T-waves, low (K<3.5) = flat T-waves, U-waves.
  • Never IV push potassium; always use infusion pump, max 10-20mEq/hr.
  • Treat high K: 1st IV calcium gluconate if dysrhythmias, 2nd insulin+glucose, 3rd Kayexalate/dialysis.

Calcium & Magnesium

  • Calcium (9.0–10.5): contracts muscles; low = Trousseau’s, Chvostek’s signs, diarrhea; high = kidney stones, constipation.
  • Magnesium (1.3–2.1): mellows muscles; low = hyperreflexia, torsades; high = decreased reflexes.

Complete Blood Count (CBC)

  • Hemoglobin (Hgb: 12-18): carries Oâ‚‚; <7 = critical transfusion trigger.
  • Hematocrit (Hct: 36-54): ratio of RBC:plasma; high = dehydration, low = fluid overload/bleeding.
  • White Blood Cells (WBC: 5,000-10,000): high = infection, low = neutropenia (watch for fever).
  • Platelets (Plt: 150,000-400,000): low = bleed risk, <50,000 = very risky.

Coagulation Studies

  • PTT (Heparin): 46-70 seconds therapeutic; >70 = hold drug, prep antidote (protamine sulfate).
  • INR (Warfarin): 2-3 therapeutic; >3 = hold, check for bleeding, prep vitamin K.
  • Platelets <50,000 = hold antiplatelets/anticoagulants.

Cardiac, Renal, Liver Labs

  • Troponin >0.5 = acute MI.
  • BNP >100 indicates CHF.
  • Creatinine >1.3 signals kidney injury; BUN >20 = dehydration.
  • Albumin <3.5, elevated ammonia, bilirubin, ALT/AST in liver failure; monitor mental status for encephalopathy.

Acid-Base, Diabetes, & Miscellaneous Labs

  • pH: 7.35–7.45; PaCOâ‚‚: 35-45; HCO₃: 22-26.
  • Glucose: 70-115, fasting <100, HbA1c <6.5%.
  • UA: specific gravity 1.003–1.030; high = concentrated/dehydrated; WBC, nitrites = infection.

Key Terms & Definitions

  • BMP — Basic Metabolic Panel, a group of key blood tests.
  • CBC — Complete Blood Count, tests WBC, RBC/Hgb/Hct, and platelets.
  • INR/PTT — Coagulation test for blood thinning medication monitoring.
  • Troponin — Protein marker for heart muscle injury.
  • BUN/Creatinine — Waste markers for kidney function.
  • Albumin — Liver-produced protein; low in liver failure.
  • Ammonia — Protein waste elevated in liver dysfunction.
  • Hypoglycemia — Low blood glucose, risk of brain death.
  • Neutropenia — Low WBC, high infection risk.

Action Items / Next Steps

  • Memorize all normal lab ranges and max "danger" values.
  • Complete related study guides for BMP, CBC, and coagulation panels.
  • Practice NCLEX-style questions focusing on safety interventions for abnormal labs.
  • Review ABG interpretation methods and key causes of acid-base imbalances.

Full transcript