Laboratory & Imaging Studies Week 7

Learning Objectives

• Ability to describe commonly ordered laboratory and imaging studies
• Knowledge of normal reference values for these studies
• Understanding of critical test results and the importance of immediate reporting

Role of the Nurse

• Specimen Collection:

  • Verify orders, ensure accurate patient identification, and educate patients
  • Practice proper hand hygiene during sample collection
  • Label samples at the bedside to prevent errors
  • Transport collected samples to the laboratory

• Imaging Studies:

  • Confirm orders and patient identification
  • Prepare patients as necessary for tests
  • Monitor patients post-examination as required

Laboratory Studies

• Blood Studies Overview:
  • Commonly performed laboratory tests include Complete Blood Count (CBC) and Basic Metabolic Panel (BMP)

Complete Blood Count (CBC)

• Components and Reference Values:
  • WBC Count: 5,000-10,000 mm³
  • Hemoglobin (Hgb): 12-18 g/dL
  • Hematocrit (Hct): 40-50%
  • RBC Count: 4.2-5.9 million mm³
  • Mean Corpuscular Volume (MCV): 80-94 fl
  • Mean Corpuscular Hgb (MCH): 27-32 pg
  • Mean Corpuscular Hgb Concentration (MCHC): 33-38%
  • Red Cell Distribution Width (RDW): 11.5-15.0%
  • Platelet Count: 100,000-400,000 mm³

Differential Count

• Neutrophils: 36-71%
• Lymphocytes: 20-50%
• Monocytes: 6-13%
• Eosinophils: 0-6%
• Basophils: 0-1%
• Band Forms: 0-1%

Basic Metabolic Panel (BMP)

• Components and Reference Ranges:
  • Sodium: 135-145 mEq/L
  • Potassium: 3.5-5.0 mEq/L
  • Calcium: 4.5-5.1 mg/dL
  • Chloride: 97-107 mEq/L
  • CO2: 22-34 mmol/L
  • Glucose: 60-100 mg/dL
  • Blood Urea Nitrogen (BUN): 8.0-20 mg/dL
  • Creatinine: 0.7-1.4 mg/dL

Complete Metabolic Panel (CMP)

• Contains 14 components, including those in the BMP

Coagulation Studies

• Prothrombin Time (PT): Reference range 10-13.1 seconds
• International Normalized Ratio (INR):
  • Normal range 0.88-1.16
  • 2.0-3.0 for patients on anticoagulant therapy
  • 2.5-3.5 for patients with mechanical heart valves
• Partial Thromboplastin Time (PTT/aPTT): Reference range 27.5-37.4 seconds; Heparin therapy monitoring reference range 58-99 seconds

Blood Cultures

• Important to collect the first sample, followed by additional samples 15 minutes apart

Critical Values

• Certain laboratory results require immediate action and should be reported without delay to ensure appropriate patient care