What is the appropriate initial management for a 6-year-old girl presenting with sudden onset vomiting, dizziness, leukocytosis, and elevated CRP?

Initial Management of Acute Febrile Illness with Leukocytosis in a 6-Year-Old

This child requires immediate hospital admission for intravenous fluids, antiemetic therapy, and urgent diagnostic evaluation to exclude serious bacterial infection, particularly given the marked leukocytosis (WBC 19.8), neutrophilia (85% granulocytes), elevated CRP (14 mg/L), and tachycardia (pulse 144). 1

Immediate Assessment and Stabilization

Vital Signs Interpretation

• Tachycardia (P 144) is concerning and requires immediate evaluation for shock, dehydration, or systemic infection 1
• Blood pressure 107/70 is acceptable for age, but the elevated heart rate suggests compensated shock or significant systemic stress 1
• SpO2 97% is reassuring but does not exclude serious illness 1

Laboratory Findings Analysis

The laboratory profile is highly concerning for bacterial infection:

• WBC 19.8 with 85% granulocytes represents significant neutrophilic leukocytosis, which in the context of fever and vomiting suggests bacterial infection rather than viral illness 1
• CRP 14 mg/L is moderately elevated and when combined with leukocytosis has 88% sensitivity for identifying serious bacterial infections in children 2
• The combination of elevated CRP and leukocytosis has a positive predictive value of at least 93% for bacterial pathology 2

Differential Diagnosis Priority

High-Risk Conditions to Exclude Immediately

Multisystem Inflammatory Syndrome in Children (MIS-C):

• This presentation meets tier 1 screening criteria: fever, vomiting (gastrointestinal symptom), elevated CRP, and neutrophilia 1
• Immediate tier 2 evaluation is warranted including troponin, BNP, ferritin, D-dimer, fibrinogen, and ECG 1
• The tachycardia is particularly concerning for cardiac involvement 1

Acute Appendicitis:

• Vomiting with leukocytosis and elevated CRP in a 6-year-old requires urgent abdominal evaluation 2
• When symptoms persist >12 hours, CRP >10 mg/L identifies 72% of appendicitis cases 2

Renal Abscess:

• The triad of fever, vomiting, and elevated inflammatory markers (leukocytosis + CRP) is characteristic 3
• All children with renal abscesses present with leukocytosis and elevated CRP 3

Bacterial Pneumonia:

• Tachycardia and systemic symptoms warrant chest examination and consideration of imaging 1
• Peripheral WBC count and CRP levels are key indicators of bacterial pneumonia 1

Initial Management Algorithm

Step 1: Immediate Interventions (First 30 Minutes)

Establish IV access and begin fluid resuscitation:

• Assess for dehydration clinically (skin turgor, mucous membranes, capillary refill) 1
• Initiate isotonic crystalloid bolus if signs of dehydration present 1

Antiemetic therapy:

• Ondansetron 0.1 mg/kg IV (maximum 4 mg) over at least 30 seconds 4
• Approved for children aged 6 months and older for vomiting 4

Obtain blood glucose immediately:

• Hypoglycemia can precipitate vomiting and altered mental status 1

Step 2: Diagnostic Evaluation (Within 2 Hours)

Tier 1 Laboratory Studies:

• Complete blood count with differential (already obtained) 1
• Complete metabolic panel including electrolytes, renal function, liver enzymes 1
• Blood culture before antibiotics 1
• Urinalysis and urine culture 3
• SARS-CoV-2 PCR and/or serology 1

Tier 2 Studies (Given Concerning Vital Signs):

• Troponin T and BNP (cardiac biomarkers) 1
• Ferritin, D-dimer, fibrinogen 1
• Procalcitonin if available 1

Imaging:

• Abdominal ultrasound to evaluate for appendicitis, renal abscess, or other intra-abdominal pathology 3
• ECG to assess for cardiac involvement given tachycardia 1
• Chest radiograph if respiratory symptoms develop or examination suggests pneumonia 1

Step 3: Empiric Antibiotic Therapy Decision

Initiate broad-spectrum IV antibiotics if:

• Clinical toxicity present 1
• Inability to maintain oral intake persists despite antiemetics 1
• Imaging reveals focal bacterial infection 1
• Patient meets criteria for sepsis (persistent tachycardia, altered perfusion) 1

Appropriate empiric regimen:

• Ceftriaxone 50-75 mg/kg/day IV (covers common bacterial pathogens including E. coli, most common in renal abscesses) 3
• Consider adding vancomycin if concern for MRSA or severe presentation 1

Step 4: Admission Criteria

This patient requires hospital admission based on: 1

• Abnormal vital signs (tachycardia) 1
• Inability to maintain oral intake (vomiting) 1
• Marked elevation in inflammatory markers (CRP ≥10 mg/dL when converted from 14 mg/L) 1
• Need for IV fluids and medications 1

Monitoring and Reassessment

Clinical improvement should occur within 48-72 hours: 1

• Monitor temperature, heart rate, respiratory rate every 4-6 hours 1
• Repeat CRP and WBC count at 24-48 hours to assess response 1
• If no improvement or clinical deterioration, escalate imaging and consider alternative diagnoses 1

Critical Pitfalls to Avoid

Do not dismiss this as simple viral gastroenteritis:

• The degree of leukocytosis (19.8) with neutrophilia (85%) is atypical for viral illness 1, 5
• Viral syndromes typically present with lymphopenia, not neutrophilia 1

Do not delay evaluation for MIS-C:

• Even without respiratory symptoms, cardiac involvement can be present 1
• Early recognition and treatment improve outcomes 1

Do not assume normal blood pressure excludes shock:

• Children can maintain blood pressure through compensatory tachycardia until late in shock 1
• Persistent tachycardia despite adequate hydration warrants ICU consultation 1

Do not overlook surgical emergencies:

• Appendicitis can present with vomiting before abdominal pain becomes prominent 2
• Renal abscess may not present with classic flank pain in young children 3