Introduction
Acute kidney injury (AKI) is a sudden fall in kidney function over hours to days, often reversible. Chronic kidney disease (CKD) is lasting damage or loss of function for more than 3 months. In children the causes and needs differ from adults: dehydration and HUS lead in AKI, congenital anomalies in CKD, and growth is a central concern.
Acute kidney injury
Definition (KDIGO)
Any of: creatinine up by ≥ 26.5 µmol/L (0.3 mg/dL) within 48 hours; creatinine 1.5 times baseline within 7 days; urine output under 0.5 mL/kg/h for 6 hours. Stages 1–3 by size of the rise or fall in urine output. Remember creatinine depends on muscle mass, so a “normal” adult value can be high for a toddler.
Haemolytic uraemic syndrome (HUS)
A thrombotic microangiopathy and the commonest cause of intrinsic AKI in young children. Triad: microangiopathic haemolytic anaemia (fragmented red cells, high LDH, negative Coombs test), thrombocytopenia and AKI.
- STEC-HUS (90%): Shiga toxin from E. coli O157 (undercooked beef, unpasteurised milk, petting farms) after bloody diarrhoea. Supportive care, dialysis in about half; no antibiotics or antimotility drugs.
- Atypical HUS: complement dysregulation, no diarrhoea, relapses; eculizumab or ravulizumab.
- Pneumococcal HUS: after pneumonia or empyema; Coombs-positive; avoid plasma.
Managing AKI
- Treat the cause: rehydrate a dry child; relieve obstruction (catheter); stop nephrotoxins.
- Strict fluid balance: when oliguric, give insensible losses (about 400 mL/m² a day) plus urine output; weigh daily.
- Hyperkalaemia: ECG; calcium gluconate to protect the heart; shift potassium into cells with nebulised salbutamol or insulin with glucose; remove it (furosemide, binders, dialysis); stop potassium intake.
- Correct acidosis, hyponatraemia, hyperphosphataemia and hypocalcaemia; control hypertension; nutrition; adjust drug doses.
- Dialysis (peritoneal in infants, haemodialysis or continuous haemofiltration) for refractory hyperkalaemia, acidosis or fluid overload (pulmonary oedema), uraemic symptoms (encephalopathy, pericarditis, bleeding), or to allow nutrition.