Rapid Cortisol Testing

Rapid Cortisol Testing in Pediatrics

Key Points

  • Point-of-care testing for adrenal function
  • Results available within 15-30 minutes
  • Critical for emergency assessment of adrenal insufficiency
  • Sample types: Saliva, blood, or urine

Introduction

Rapid cortisol testing provides quick assessment of adrenal function in pediatric patients, essential for diagnosing and monitoring adrenal insufficiency, congenital adrenal hyperplasia (CAH), and other endocrine disorders. This point-of-care testing enables prompt clinical decision-making in both emergency and outpatient settings.

Testing Methods

Sample Collection

  • Salivary Sampling:
    • Non-invasive collection
    • Special collection devices
    • Morning sample (7-9 AM)
    • No food/drink 30 minutes prior
  • Blood Sampling:
    • Serum or plasma
    • Volume: 50-100 μL
    • EDTA or heparin tubes
    • Timing considerations critical
  • Urine Collection:
    • 24-hour collection preferred
    • First morning sample alternative
    • Proper storage requirements

Testing Procedure

  1. Pre-analytical Phase:
    • Patient preparation
    • Proper timing selection
    • Sample collection protocol
    • Sample handling guidelines
  2. Analytical Phase:
    • Immunoassay-based methods
    • Quality control checks
    • Calibration verification
    • Temperature monitoring

Result Interpretation

Reference Ranges

  • Morning Serum Cortisol:
    • Newborns: 1-24 μg/dL
    • Infants: 2-11 μg/dL
    • Children: 3-21 μg/dL
    • Adolescents: 5-23 μg/dL
  • Salivary Cortisol:
    • Morning: 0.1-0.7 μg/dL
    • Evening: <0.1 μg/dL
    • Midnight: <0.01 μg/dL
  • 24-hour Urinary Free Cortisol:
    • Children: 1.4-20 μg/24h
    • Adolescents: 2.6-37 μg/24h

Critical Values

  • Low Values (<3 μg/dL):
    • Suggestive of adrenal insufficiency
    • Requires immediate evaluation
    • Consider stress dosing
  • High Values (>25 μg/dL):
    • Possible Cushing syndrome
    • Stress response
    • Medication effect

Clinical Applications

Primary Indications

  • Emergency Assessment:
    • Suspected adrenal crisis
    • Acute illness in CAH
    • Pre-operative screening
    • Trauma evaluation
  • Monitoring:
    • CAH management
    • Steroid therapy
    • Adrenal insufficiency
    • Cushing syndrome

Special Considerations

  • Timing Factors:
    • Diurnal variation
    • Stress response
    • Recent medication use
    • Illness impact
  • Interfering Factors:
    • Medications (glucocorticoids)
    • Stress conditions
    • Recent food intake
    • Physical activity

Treatment Implications

  • Emergency Management:
    • Stress dose steroids
    • Fluid resuscitation
    • Electrolyte correction
    • Close monitoring
  • Long-term Management:
    • Dose adjustments
    • Monitoring frequency
    • Stress coverage plans
    • Patient education

Quality Assurance

  • Regular calibration
  • Control testing
  • Staff training
  • Result documentation
  • External quality assessment


Further Reading
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