Haemolytic Uraemic Syndrome
Definition
- Haemolytic anaemia (microangiopathic)
- Thrombocytopenia
- Acute renal failure
Epidemiology
- One of the main causes of AKI in children
- Mainly affects children under the age of 5 years
- Often preceded by bloody diarrhea
Causes
Secondary causes
- Shiga toxin-producing Escherichia coli (STEC) - 90% of cases = Typical HUS
usually children 6 month - 5 years of age
- Shigella dysenteriae
- HIV
- Severe S. pneumoniae -infection
- Drugs, e.g Quinine
- Lupus
Primary causes
- Complement dysregulation (mutation or antibodies)
Atypical HUS = all non STEC cases, worse outcome, may occur at any age
Mechanism:
Endothelial damage and inflammation in small blood vessels in kidneys, brain, intestines; multiple small vessel thromboses due to platelet activation; red blood cells passing through damaged vessels break down
Important points in history
- Diarrhoea? (usually bloody)
- Followed by febrile illness, pallor
- Hematuria
Important points on examination
- Fever
- Pallor
- Petechiae
- Dehydration secondary to Gastroenteritis
- Edema
- Hypertension
- Behavior changes
Additional symptoms:
Neurologic symptoms (seizures, somnolence) 25%
Hemorragic colitis, bowel necrosis and perforation
Hepatomegaly and increased transaminases
Investigations:
-
FBC:
Hemoglobin level usually less than 8 g/dL
Thrombocytopenia - usually 20 - 50 Tsd/ µl
Leucocytosis (often seen in typical HUS)
- PBF: red cell fragmentation
- LFTs: elevated LDH and unconjucated Bilirubin (hemolysis)
- Creatinine: raised
- Electrolytes if available (hyperkalemia or hypokalemia in GE), metabolic acidosis, hyponatremia, hypocalcemia)
- Blood pressure
Differential diagnosis
Disseminated intravascular coagulation (DIC) related to sepsis
Systemic vasculitis
Management
- Monitor and treat as for acute kidney injury
- Monitor and treat blood pressure Hypertension (Nifedipin)
- Optimize fluid balance
- Transfuse whole blood, if severe anaemia
- Transfuse platelets only, if bleeding or an invasive procedure is required
- Avoid nephrotoxic drugs
- About 50% of patients need dialysis (see PD protocol); usually kidney recovery seen
in 1-2 weeks
Recovery is usually complete if the child survives the acute phase of disease
Follow up
- Blood pressure and creatinine
- Should be seen in renal clinic at least 2-3 times or until blood pressure is normal
without antihypertensives and creatinine has returned to normal level