Synopsis
Recognise defective mitochondrial haem synthesis, distinguish inherited, clonal and reversible acquired causes, interpret ring sideroblasts correctly, and treat the driver while preventing transfusional iron injury.
- Sideroblastic anaemia describes ineffective erythropoiesis in which iron accumulates within mitochondria encircling erythroblast nuclei as ring sideroblasts on marrow iron staining.
- It is a morphological mechanism rather than one disease: causes include inherited ALAS2-related disease, myelodysplastic neoplasms, alcohol, medicines, copper deficiency and lead toxicity.
- The mean cell volume may be low, normal or high; a dimorphic film and raised ferritin or transferrin saturation can suggest iron-loaded ineffective erythropoiesis.
- Ring sideroblasts require a bone-marrow aspirate stained for iron and must be distinguished from ordinary sideroblasts that lack the characteristic perinuclear mitochondrial distribution.
- History should specifically cover alcohol, isoniazid, linezolid, chloramphenicol, zinc exposure, bariatric surgery, occupational lead and family or childhood anaemia.
- Copper deficiency may follow gastrointestinal surgery, malabsorption or excess zinc and can produce anaemia, neutropenia and neurological disease that mimics myelodysplasia.
- Pyridoxine responsiveness is characteristic of some ALAS2-related disease and selected drug-associated cases, but empiric indefinite high doses can cause sensory neuropathy.
- Clonal sideroblastic anaemia requires integrated marrow morphology, blast count, cytogenetics and molecular testing such as SF3B1 rather than classification by ring percentage alone.
- Remove a reversible toxin or medicine when clinically safe, replace documented deficiency and involve occupational services or toxicology where exposure persists.
- Chronic ineffective erythropoiesis and transfusions can load iron even without routine oral supplementation, requiring ferritin trends and specialist organ iron assessment.
Key red flags
New severe cytopenias, circulating blasts, infection or bleeding needs urgent myeloid-neoplasm assessment rather than routine nutritional follow-up.
Investigation priorities
Define cell size, dimorphism and other cytopenias.
Management branches
Persistent anaemia has atypical indices, dimorphism or unexpectedly high iron stores.
- Review count trajectory, reticulocytes, film and iron measures and stop reflex iron prescribing until true deficiency is demonstrated.
- Take a detailed alcohol, medicine, zinc, surgery, occupation and family history, then test copper and lead where exposure makes them plausible.
- Arrange marrow aspirate, trephine, iron stain and clonal studies through haematology when anaemia persists or additional cytopenias suggest myelodysplasia.
Key medicines
PyridoxineA haematologist may supervise an oral therapeutic trial, commonly 50–200 mg daily depending on suspected mechanism, with a defined blood-response review and lowest effective maintenance dose.Prolonged high-dose exposure can cause sensory neuropathy; document indication, neurological baseline and response rather than continuing an ineffective trial indefinitely.
Copper replacementUse an oral or intravenous elemental-copper regimen selected by severity and absorption, with specialist monitoring of copper, zinc, counts and neurological response.Identify and remove the driver, avoid unmonitored over-replacement and recognise that neurological recovery may lag or remain incomplete after blood counts normalise.