Essential Blood Tests for Pediatric Shock
In a child with suspected shock, obtain glucose, calcium, lactate, complete blood count with differential, and coagulation studies (PT/INR) immediately, as these guide critical resuscitation decisions and can be life-saving. 1
Core Laboratory Panel
The American College of Critical Care Medicine guidelines explicitly recommend monitoring specific blood parameters in pediatric shock 1:
Immediate Priority Tests (Results needed within minutes):
Glucose: Hypoglycemia (<3 mmol/L) can precipitate seizures and must be corrected immediately 2. Maintain glucose 80-150 mg/dL during resuscitation 1
Ionized Calcium: Hypocalcemia impairs cardiac contractility and must be corrected for effective resuscitation 1
Lactate and Base Deficit: These are sensitive markers of tissue hypoperfusion severity 1. Lactate is the preferred marker over base deficit for assessing tissue hypoxia 3. Target lactate normalization and ScvO2 >70% 1
Complete Blood Count: Hemoglobin should be maintained ≥10 g/dL to optimize oxygen delivery 1. Serial measurements are more sensitive than initial values for detecting ongoing blood loss 3
Secondary Tests (Results within 60 minutes):
Coagulation Studies (PT/INR): Essential for identifying coagulopathy and guiding fresh frozen plasma administration 1. FFP is recommended for prolonged INR but as an infusion, not bolus 1
Electrolytes: Monitor sodium and potassium, particularly as severe hyperkalemia (>5.5 mmol/l) indicates high-risk patients 2
Anion Gap: Helps assess metabolic acidosis severity 1
Monitoring Strategy
The guidelines emphasize continuous monitoring rather than single measurements 1. Serial lactate measurements provide early objective evaluation of response to therapy 3. The therapeutic endpoints include normalizing lactate, anion gap, and INR alongside clinical perfusion parameters 1.
Common Pitfalls to Avoid:
- Don't wait for laboratory confirmation before starting resuscitation—begin fluid boluses and obtain blood during IV access 2, 1
- Initial hemoglobin values near normal may mask serious bleeding—serial measurements are essential 3
- Lactate is more specific for tissue hypoperfusion than base deficit 3, though both correlate with shock severity
- Capillary refill time alone is insufficient—combine with other clinical and laboratory markers 4
Biomarkers for Specific Contexts
While not part of routine initial management, procalcitonin can help differentiate septic shock from other causes when the diagnosis is uncertain 5, 6. A procalcitonin >2 ng/mL identifies severe bacterial disease, and >20 ng/mL predicts septic shock with high accuracy 6. However, this should not delay empiric treatment.
The key principle is that these tests must be rapidly available and serially monitored to guide ongoing resuscitation, not simply obtained once at presentation 1.