Haemolytic uraemic syndrome: SAQ

This boy has typical STEC-associated haemolytic uraemic syndrome. The triad of microangiopathic haemolytic anaemia (haemoglobin of 57 with schistocytes, elevated LDH, undetectable haptoglobin), thrombocytopenia (platelets 42), and acute kidney injury (creatinine 195) following bloody diarrhoea eight days prior, with normal coagulation studies, is diagnostic. The normal prothrombin time and APTT are essential because they distinguish HUS from disseminated intravascular coagulation, where the coagulation cascade is systemically consumed. ^[1]

Question 1 (10 marks)

Outline your immediate management of this child, including fluid management, blood product support, and the indications for renal replacement therapy. ^[1]

The overriding principle is meticulous supportive care because no specific therapy reliably alters the course of STEC-HUS. I would first assess and stabilise the airway, breathing, and circulation, with careful attention to fluid balance. This is the most challenging aspect because the child may be volume-depleted from the preceding gastroenteritis but is simultaneously at risk of fluid overload from acute kidney injury. I would assess volume status clinically and with daily weights, input-output charts, and blood pressure monitoring. If the child is volume-depleted and still passing urine, cautious rehydration with isotonic saline is appropriate. If he is oliguric or anuric, I would fluid-restrict to insensible losses plus urine output to prevent pulmonary and cerebral oedema. ^[1]

For the severe anaemia with haemoglobin of 57 g per litre, I would transfuse packed red cells cautiously, monitoring for volume overload, because rapid expansion of intravascular volume can worsen hypertension and pulmonary oedema. I would avoid routine platelet transfusion because the platelets may be consumed in the microvascular thrombi, potentially worsening the thrombotic process. Platelets are reserved for active bleeding or before invasive procedures such as central line insertion. Fresh frozen plasma is not indicated because coagulation studies are normal. ^[1]

I would monitor and treat electrolyte disturbances. Hyperkalaemia is common and dangerous: treatment includes calcium gluconate for cardiac stabilisation, insulin-dextrose and salbutamol for intracellular potassium shift, and sodium bicarbonate for metabolic acidosis. The indications for renal replacement therapy are refractory hyperkalaemia unresponsive to medical therapy, severe metabolic acidosis, fluid overload unresponsive to diuretics, and uraemic complications such as pericarditis or encephalopathy. Peritoneal dialysis is the preferred mode in young children, though haemodialysis or continuous renal replacement therapy may be used depending on the clinical context. I would involve the paediatric nephrology team early and transfer to a tertiary centre if dialysis is anticipated. ^[1]

I would also send stool cultures for E. coli O157:H7 and Shiga toxin PCR, though these may be negative by the time HUS develops. I would avoid antibiotics and antimotility agents. I would screen for neurological involvement, which occurs in 20 to 40 percent of cases and predicts a worse outcome. ^[1]