Table 2.

Summary of laboratory tests to confirm haemolysis

TestFinding in haemolysisCause
Reticulocyte countRaisedBone marrow response to anaemia can lead to macrocytosis
Lactate dehydrogenaseRaisedReleased from the breakdown of red blood cells
Unconjugated bilirubinRaisedIncreased haemoglobin breakdown
HaptoglobinDecreasedBinds to free haemoglobin
Direct antiglobulin testPositive in immune cases of haemolytic anaemiaDetects immunoglobulins or complement bound in vivo to red cell membranes
Blood filmMay show abnormal red blood cellsMorphology dependent on the cause of haemolysis
Urinalysis for haemoglobinuriaA positive urine dipstick for blood, but microscopy negative of red blood cellsOccurs in severe acute intravascular haemolytic anaemia that exhausts haptoglobin-binding capacity; free haemoglobin is filtered by the glomerulus and haemoglobinuria occurs