Overview

Sideroblastic anaemias are a group of conditions in which haemoglobin is insufficiently synthesised due to defective iron use, even if iron studies are normal/elevated. They are called sideroblastic due to ferritin accumulating in the mitochondria of immature red blood cells. These mitochondria form a ring around the nucleus and along with the deposition of ferritin, they form a ring sideroblast.

Sideroblastic anaemias can be congenital or acquired.

It may be helpful to look at the chapter on Anaemia: Data Interpretation alongside reading this section to help wrap your head around when to suspect what type of anaemia.

Epidemiology

  • Acquired sideroblastic anaemia is more common
  • Those with acquired sideroblastic anaemia often go on to develop myelodysplastic syndrome (MDS)

Causes

Congenital sideroblastic anaemia

Acquired sideroblastic anaemia

Example History

A 45-year-old man has tiredness that has been worsening over the last 6 months. On examination, he is pale. He has been on treatment for tuberculosis for the past 10 years.

Investigations:

Haemoglobin:102 g/L(130 – 180 g/L)
Platelets:205 x 109/L(150 – 450 x 109/L)
Mean cell volume (MCV):75.0 fL(76.0 – 98.0 fL)
White blood cells:8.5 x 109/L(3.00 – 10.0 x 109/L)
Serum iron:15.3 μmol/L(11.6 – 35.0 μmol/L)
Serum ferritin:370 ng/mL(25 – 350 ng/mL)
Transferrin saturation:63 %(20 – 50 %)
Blood film:Basophilic stippling

Presentation

There are no specific signs or symptoms of sideroblastic anaemia. Patients have general features of anaemia such as:

Investigations

Overview

  • Full blood count (FBC):
    • Haemoglobin low
    • MCV: can be low/normal/increased
  • Blood film:
    • Hypochromic cells
    • Basophilic stippling of red blood cells
      • Basophilic stippling is a sign of disturbed erythropoiesis
  • Haematinics:
    • Serum iron: usually high
    • Ferritin: usually high
    • Transferrin saturation: usually high
  • Bone marrow biopsy and examination:
    • Shows ring sideroblasts and is diagnostic

Management

All patients

  • 1st-line: supportive management with transfusions if necessary
  • Patients should avoid alcohol and vitamin C intake as these can increase iron absorption

Prognosis

  • Reversible causes such (e.g. alcohol) have a better prognosis if the underlying cause is managed
  • Idiopathic sideroblastic anaemia and myelodysplastic syndrome have a median survival of around 3 years
  • Idiopathic sideroblastic anaemia alone has a median survival of around 5 years

Author