Heredetory Spherocytosis

Question 1

What are the follow up tests for hereditary spherocytosis diagnosis?

Answer 1

Osmotic fragility of RBCs
- measure RBCs resistance to osmotic stress, measure cell
volume surface area and membrane function
- incubating in varying concentrations of NaCl (RBCs cant respond - they
cant expand so burst)
- spherocytes can’t expand like normal RBCs due to decreased
SA:volume ratio
- lysis begins at higher concentrations of NaCl
- incubation at 37 degrees for 24 hours to increase sensitivity
- shows an increased fragility with a shift to the left in the osmotic
fragility curve (cf thalassaemia shifts to the right)

Rule out other causes of HA with DAT (will appear normal, excluding autoimmune HA)

Eosin-5-malemide staining:
- Staining agent the shows a left shift and decreased intensity in HS.
- HS shows a mean channel fluorescence due to membrane band 3
deficiency

Question 2

What is the clinical picture?

Answer 2

Sperocytes - microspheres

Increased red cell destruction:

• increased indirect bilirubin
• increased urobiligen excretion

Anaemia

Retic count: 5-20%

Spherocytes are selectively trapped and destroyed by spleen - damage spleen as they can’t navigate splenic architecture