What is the appropriate management for a 7-year-old female child with vomiting, hematemesis, loose stools, and acute kidney injury?

Differential Diagnosis and Management of a 7-Year-Old with Vomiting, Hematemesis, Diarrhea, and AKI

This child requires immediate assessment for severe dehydration with aggressive IV fluid resuscitation, followed by investigation for hemolytic uremic syndrome (HUS) and acute gastric mucosal lesions as the most likely life-threatening causes of this presentation.

Immediate Assessment and Stabilization

Evaluate Dehydration Severity

• Assess for signs of severe dehydration (≥10% fluid deficit): severe lethargy or altered consciousness, prolonged skin tenting (>2 seconds), cool and poorly perfused extremities, decreased capillary refill, rapid deep breathing (acidosis), tachycardia, and hypotension 1
• Measure vital signs, weight, and mental status to determine if this constitutes shock or near-shock, which is a medical emergency 1, 2
• The presence of AKI with vomiting and diarrhea strongly suggests severe volume depletion 3, 4

Immediate Fluid Resuscitation

• For severe dehydration with AKI, initiate immediate IV rehydration with 20 mL/kg boluses of Ringer's lactate or normal saline until pulse, perfusion, and mental status normalize 1, 2, 5
• This may require two IV lines or alternate access sites (venous cutdown, femoral vein, intraosseous infusion) 1
• Once consciousness returns to normal, transition to oral rehydration solution (ORS) to complete the remaining estimated fluid deficit 2, 5
• Continue replacing ongoing losses with 10 mL/kg ORS for each watery stool and 2 mL/kg for each vomiting episode 6, 2

Critical Differential Diagnoses

Hemolytic Uremic Syndrome (HUS)

The combination of bloody diarrhea (hematemesis may represent swallowed blood from GI source), vomiting, and AKI is classic for HUS and must be ruled out immediately.

• Obtain urgent laboratory studies: complete blood count with peripheral smear (looking for schistocytes and helmet cells), platelet count, LDH, haptoglobin, direct Coombs test, serum creatinine, and urinalysis 7
• HUS classically presents with the triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury 7
• Check stool PCR for Shiga toxin-producing E. coli, Shigella, and consider norovirus, as norovirus-associated HUS has been reported in pediatric patients with a milder course 7
• Norovirus-associated HUS in children typically has better outcomes than STEC-HUS, but still requires aggressive supportive care 7

Acute Gastric Mucosal Lesions (AGML)

Hematemesis in the setting of severe dehydration and stress suggests acute gastroduodenal mucosal injury.

• AGML can present with sudden onset epigastric pain, vomiting, hematemesis, and melena following physical stress (severe dehydration qualifies) 8
• Endoscopic findings include erosions, hemorrhagic gastritis, and acute ulcers that can develop rapidly 8
• The severe dehydration and metabolic stress from volume depletion are sufficient causes for AGML 8

Prerenal AKI from Severe Dehydration

• The most common cause of AKI in this presentation is prerenal failure from severe volume depletion 3
• Cyclical vomiting syndrome can cause severe dehydration leading to anuric renal failure, which typically resolves with aggressive rehydration 3
• Obtain serum electrolytes immediately to assess for severe hypokalemia and metabolic alkalosis, which can occur with persistent vomiting and lead to cardiorespiratory complications 4

Diagnostic Workup

Immediate Laboratory Studies

• Complete blood count with peripheral smear (assess for anemia, thrombocytopenia, schistocytes) 7
• Comprehensive metabolic panel including serum creatinine, BUN, electrolytes (sodium, potassium, chloride, bicarbonate) 1, 4
• LDH, haptoglobin, direct Coombs test to evaluate for hemolysis 7
• Urinalysis to check for proteinuria, hematuria, and assess urine concentration 7
• Stool studies: culture for bacterial pathogens (Shigella, Salmonella, Campylobacter), Shiga toxin assay, and PCR for viral pathogens including norovirus 1, 7

Additional Considerations

• Blood pressure monitoring is essential, as HUS commonly presents with hypertension 7
• Assess for complement abnormalities if HUS is confirmed and no infectious etiology is identified, though this is less urgent than initial stabilization 7

Management Strategy

Fluid Management

• Continue IV fluid resuscitation until hemodynamically stable, then transition to ORS 2, 5
• Monitor urine output closely as oliguria/anuria indicates severe AKI requiring potential dialysis support 3, 4
• Avoid central venous lines if possible due to high thrombosis risk in nephrotic/HUS states, but if required for repeated interventions, provide prophylactic anticoagulation 1

Gastrointestinal Management

• Hold oral intake initially if hematemesis is active until upper GI source is evaluated 8
• Consider urgent gastroenterology consultation for possible endoscopy if hematemesis persists or is severe 8
• Once vomiting controlled and no active hematemesis, resume age-appropriate diet with easily digestible foods (starches, cereals, yogurt, fruits, vegetables) 6, 2

Antiemetic Therapy

• Ondansetron may be administered to facilitate oral rehydration once adequate IV hydration is achieved (only after hemodynamic stability) 6
• Recent evidence suggests ondansetron does not increase AKI risk and may actually improve outcomes 9

Antibiotic Considerations

• Stool cultures are indicated for dysentery (bloody diarrhea) 1
• Do NOT give antibiotics empirically if HUS is suspected, as antibiotics for STEC infection may worsen HUS by increasing Shiga toxin release 7
• Wait for stool culture results before initiating antibiotics unless there is clear evidence of invasive bacterial infection with high fever 6, 2

Renal Support

• If oliguria/anuria persists despite adequate fluid resuscitation, prepare for renal replacement therapy (hemodialysis or peritoneal dialysis) 4
• Furosemide may be used cautiously for oliguria once euvolemia is achieved, but high doses (>6 mg/kg/day) should not be given for >1 week due to ototoxicity risk 1

Key Pitfalls to Avoid

• Do not delay IV fluid resuscitation while awaiting diagnostic results—start immediately based on clinical assessment 2, 5
• Do not use plain water, juice, or sports drinks for rehydration—these lack appropriate sodium concentration (50-90 mEq/L) 2
• Do not give antibiotics empirically if HUS is suspected until STEC is ruled out 7
• Do not allow ad libitum drinking of large ORS volumes in thirsty patients, as this worsens vomiting 2
• Do not assume hematemesis is from esophageal source—consider swallowed blood from epistaxis or lower GI bleeding in context of HUS 7

Monitoring and Reassessment

• Reassess hydration status every 2-4 hours during initial resuscitation 6, 2
• Monitor for signs of HUS progression: worsening anemia, thrombocytopenia, rising creatinine, hypertension 7
• Serial electrolyte monitoring is essential, particularly potassium in the setting of AKI and ongoing GI losses 4
• Daily weights and strict intake/output monitoring 1