鐵芽球性貧血

Buzzwords → Dx

Diagnostic Criteria

• Ringed sideroblasts ≥15 % of erythroblasts on Prussian blue iron stain (or ≥5 % with SF3B1 mutation = MDS-RS per WHO 5e).
• Iron studies: elevated serum iron, ferritin, TSAT (vs IDA which has low values).
• Marrow biopsy + cytogenetics + NGS to subtype.
• Genetic testing for hereditary (ALAS2, SLC25A38, GLRX5, ATP12, TRNT1, ABCB7).
• Lead level if exposure suspected (children with pica, occupational, water sources).
• Drug review (INH, alcohol, chloramphenicol).
• Copper, ceruloplasmin if neuropathy + neutropenia.

Workup

• CBC + smear + retic (basophilic stippling in lead).
• Iron studies (Fe, TIBC, ferritin, TSAT).
• B12, folate, B6 (pyridoxine).
• Lead level.
• Marrow biopsy with Prussian blue stain + karyotype + NGS panel (SF3B1, others).
• Copper + ceruloplasmin if non-clonal sideroblastic suspected.
• Drug history + alcohol use review.

Treatment Algorithm

flowchart TD
  A[Sideroblastic anemia confirmed] --> B{Cause}
  B -- hereditary X-linked ALAS2 --> C[Pyridoxine 50-200 mg/d trial<br>often dramatic response]
  B -- MDS-RS / SF3B1 mutation --> D[Luspatercept first-line<br>COMMANDS trial<br>or HMA in higher-risk MDS]
  B -- lead poisoning --> E[Remove exposure + chelation<br>EDTA / DMSA / dimercaprol]
  B -- isoniazid / alcohol / chloramphenicol / drug --> F[Discontinue / replace<br>+ pyridoxine]
  B -- copper deficiency --> G[Copper repletion<br>oral or parenteral; remove zinc excess]
  C --> H[Iron overload monitoring<br>chelation if ferritin >1000 or LIC high]
  D --> H
  H --> I[Deferasirox / deferoxamine / deferiprone<br>per iron loading]

Pearls / Pitfalls

• High iron + high ferritin + low Hb = sideroblastic, not IDA. Don't give iron — worsens overload.
• Hereditary X-linked sideroblastic anemia can dramatically respond to pyridoxine (B6) — always trial in suspected hereditary cases.
• MDS-SF3B1 (MDS-RS) has favorable prognosis among MDS — treat with luspatercept (COMMANDS) or watch.
• Lead poisoning: classical microcytic with basophilic stippling, abdominal pain, peripheral neuropathy (wrist drop), behavioral/cognitive. Pediatric pica + water/paint exposure.
• Isoniazid (INH) depletes B6 → sideroblastic + peripheral neuropathy. Always co-prescribe pyridoxine 25–50 mg/d with INH.
• Copper deficiency (post-gastric bypass, zinc-rich denture cream, parenteral nutrition without copper) → sideroblastic + neutropenia + ataxia + myelopathy. Replete copper.
• Iron overload is universal in chronic sideroblastic — iron chelation when ferritin >1000 or hepatic iron concentration high. Avoid additional iron supplements.
• Alcohol chronic — multifactorial (sideroblastic + folate deficiency + direct toxicity) — abstinence + nutrition.
• Chloramphenicol — reversible sideroblastic with high doses; rarely used now.

Cross-references

• IDA — opposite iron pattern
• MDS-SF3B1 — clonal sideroblastic
• Iron Chelation
• Iron Studies — sideroblastic pattern
• Anemia Workup

相關題目

• Q-121 — Sideroblastic anemia — pyridoxine response
• Q-122 — Sideroblastic anemia — copper deficiency mimic
• Q-123 — Sideroblastic anemia — lead poisoning

Sources