Anuric Child With Shiga Toxin–Associated HUS
A 4-year-old boy presents with 3 days of bloody diarrhea followed by lethargy and 12 hours of anuria. Weight is 16 kg, BP 128/86 mmHg (95th percentile 112/74), pulse 140/min, and he has periorbital edema and crackles at both bases. Hemoglobin is 7.2 g/dL, platelets 32,000/microL, creatinine 3.8 mg/dL (baseline 0.3), potassium 6.4 mmol/L, bicarbonate 12 mmol/L, sodium 132 mmol/L, and BUN 84 mg/dL. Blood smear shows schistocytes, and LDH is elevated.
1. State your immediate management of hyperkalemia and fluid overload and how you would decide on dialysis modality.
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Immediate priorities. This child has oligoanuric acute kidney injury with severe hyperkalemia (6.4 mmol/L), fluid overload, and acidosis. Obtain an ECG immediately. Give intravenous calcium gluconate for cardiac membrane stabilization if there are ECG changes. Shift potassium intracellularly with insulin plus glucose and nebulized salbutamol; consider sodium bicarbonate if severely acidotic. Use a potassium binder as adjunctive therapy. Stop all potassium intake and nephrotoxins.
Dialysis decision. Dialysis is indicated for refractory hyperkalemia, severe fluid overload with respiratory compromise, uremic complications, or severe acidosis. Do not wait for a single numeric threshold if the child is symptomatic. Because he is hypertensive, edematous, and has crackles, ultrafiltration is needed.
Modality. If he is hemodynamically unstable or needs precise continuous fluid removal, continuous renal replacement therapy is preferred. Peritoneal dialysis can be effective in HUS but is less useful for rapid potassium correction and may be difficult with abdominal distension. The choice depends on local resources and team expertise. In STEC-HUS, avoid platelet transfusion unless active bleeding or an invasive procedure is planned, and avoid antimotility agents.
2. How would you counsel the family about the acute illness and the follow-up plan after discharge?
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Counseling. Explain that HUS is a supportive-care disease and most children survive the acute episode, but renal and neurologic complications can occur. Do not promise full recovery. Discuss that dialysis is temporary in many cases but may be needed for days to weeks. Avoid anti-diarrheal drugs and unnecessary antibiotics. Monitor for seizures, hypertension, and worsening anemia.
After recovery. Follow blood pressure, urinalysis, proteinuria, and creatinine for years because hypertension and CKD can appear later. Counsel about returning promptly with bloody diarrhea or decreased urine output. In STEC-HUS complement is usually normal; atypical HUS requires different evaluation, but this presentation is typical. Ensure vaccination status and nutrition are addressed.
3. What features would make you question STEC-HUS and consider complement-mediated atypical HUS, and what would you do differently?
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Questioning the diagnosis. Consider atypical HUS if there is no preceding bloody diarrhea, a family history of HUS, recurrent episodes, onset after an infection not caused by Shiga toxin, or persistent renal failure beyond the expected course. Severe extrarenal disease, especially neurologic involvement, also raises concern. In atypical HUS, ADAMTS13 is usually normal, complement abnormalities may be present, and Shiga toxin testing is negative.
What changes. For suspected complement-mediated atypical HUS, involve pediatric nephrology urgently and consider eculizumab after appropriate meningococcal vaccination and antibiotic prophylaxis. Do not give eculizumab routinely for typical STEC-HUS. Supportive care and dialysis remain the mainstays for STEC-HUS. The key is to avoid both missing atypical HUS and exposing a typical STEC-HUS patient to unnecessary complement blockade.