Laboratory features

Haematological abnormalities:

• red cells:
  • anaemia, usual values 7-9 gHb/dL
  • fragmented red blood cells - schistocytes, helmet cells, triangle forms - in peripheral blood smear
  • normocytic, normochromic
  • marked reticulocytosis; occasional nucleated red cell
  • haemolysis - increased serum indirect bilirubin, LDH, and serum haemoglobin; absent haptoglobin
  • negative Coomb's test
• platelets - usually around 50x10^9/L - reduced by consumption in microthrombi
• leucocytes:
  • neutrophil leucocytosis
  • a poor prognosis is associated with leucocyte counts of greater than 20x10^9/L
• kaolin clotting time and prothrombin time are usually normal; a clotting abnormality is suggestive of septicaemia

Biochemical abnormalities:

• uraemia, out of proportion to the mild degree of apparent dehydration
• hyponatraemia is common, which may be a consequence of diarrhoea and vomiting, or a result of endothelial damage causing capillary leak.
• hypoalbuminaemia occurs in severe cases

Urine:

• generally HUS presents with oliguria but patients can present with polyuria - a proteinuria of typically, 1-2g of protein per day