Sideroblastic anaemia

Failure to incorporate heme into protoporphyrin → iron accumulates (esp. mitochondria).

• inherited
  • e.g, ALA-synthetase deficiency; or abnormal B12 metabolism
• acquired
  • alcohol (most common)
  • drugs - anti-TBs (INH, pyrazinamide, cycloserine, those who have anti-B6 properties); chloramphenicol
  • lead poisoning
  • copper deficiency * Cu act as cofactor in ferrochelataste
  • zinc toxicity → impairs Cu absorption
  • myelodysplastic syndrome

Dx

Sideroblastic anemia can be either microcytic or macrocytic. (normal or increaed MCV)

some are normochromic, some are hypochromic → increased RDW

Excess Fe++ in the cell ⇒ ringed sideroblasts on Prussian blue staining (the most accurate test)

Excess Fe++ in the cytoplasm ⇒ Basophilic stippling can occur in any cause of sideroblastic anemia.

Marked erythroid hyperplasia because of ineffective erythropoiesis (so, it does not actually increase reticulocytes in peripheral blood)

Elevated serum iron and ferritin as well as transferrin saturation

Both microcytic and macrocytic anemia give a low reticulocyte count except 3 gene deficient alpha thalassemia

Other causes of increased reticulocyte count are blood loss and hemolysis.

Treatment

• B6 supplementation
• Avoid alcohol
• Review meds that affect mitochondrial function
• Review history for lead exposure; nutrition, Zinc supplements