Hereditary spherocytosis

The diagnosis of HS is made when there is:

• Increased red-cell turnover (reticulocytosis) with or without anaemia

• Typical spherocytes on the blood smear

• Associated absence of an immune cause (negative direct anti-globulin test [DAT]).

Diagnosis according to severity[1]Eber SW, Armbrust R, Schroter W. Variable clinical severity of hereditary spherocytosis: relation to erythrocytic spectrin concentration, osmotic fragility, and autohemolysis. J Pediatr. 1990;117:409-16. http://www.ncbi.nlm.nih.gov/pubmed/2391596?tool=bestpractice.com

HS can be clinically classified according to the severity of the anaemia and symptoms. The assessment of HS severity should be made when the patient is well.

Trait

• Haemoglobin: normal

• Reticulocytes: <3%

• Bilirubin: <17 micromol/L (<1 mg/dL)

• Splenectomy: not required.

Mild

• Haemoglobin: 11 to 15 g/dL (110-150 g/L)

• Reticulocytes: 3% to 6%

• Bilirubin: 17 to 34 micromol/L (1-2 mg/dL)

• Splenectomy: usually not necessary.

Moderate

• Haemoglobin: 8 to 12 g/dL (80-120 g/L)

• Reticulocytes: >6%

• Bilirubin: >34 micromol/L (>2 mg/dL)

• Splenectomy: may be necessary before puberty.

Severe

• Haemoglobin: <6 to 8 g/dL (<60-80 g/L)

• Reticulocytes: >10%

• Bilirubin: >51 micromol/L (>3 mg/dL)

• Splenectomy: necessary, delay until >6 years of age if possible.