investigations

Last reviewed 01/2018

Investigations include:

• blood smear - spherocytes, small cells which have lost their central pallor, and increased reticulocytes, except in aplastic and megaloblastic crises
• incubated osmotic fragility test - confirms presence of spherocytes but does not permit hereditary spherocytosis to be distinguished from other spherocytic haemolytic disorders such as autoimmune haemolytic anaemia. This is not reliable until six months of age.
• bone marrow - normoblastic erythroid hyperplasia
• indirect-reacting serum bilirubin and increased urobilinogen - but no urinary bilirubin
• negative Coomb's test
• increased mean corpuscular haemoglobin concentration (MCHC) - often greater than 36 g/dl