Iron Overload and Chelation
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Direct answer
Every unit of transfused red cells deposits roughly 200-250 mg of iron, and the body has no excretory pathway for it — a transfusion-dependent thalassaemia major patient therefore accumulates cardiac, hepatic and endocrine iron that kills in the second and third decades unless chelated. The transfusional program starts chelation once serum ferritin exceeds about 1000 µg/L or after 10-20 transfusions, typically around two to three years of age, guided by serial ferritin and, more dependably, liver iron concentration and myocardial T2* cardiac MRI. Three chelators anchor practice: parenteral deferoxamine, oral deferiprone (the most effective at removing myocardial iron), and oral once-daily deferasirox; combination therapy rescues severe cardiac loading. Hereditary haemochromatosis, by contrast, is iron-overload without transfusion and is treated by venesection first.
What you must remember
- Burden arithmetic: each red-cell unit adds 200-250 mg iron; a monthly two-unit transfusion programme deposits grams per year, saturating transferrin and generating toxic non-transferrin-bound iron taken up avidly by heart, liver and endocrine glands.
- When to start: ferritin persistently above 1000 µg/L, or after 10-20 transfusions in thalassaemia major — whichever comes first per treating-centre protocol.
- Monitoring hierarchy: serial ferritin (trend, not single value); liver iron concentration by MRI R2 or biopsy (above about 7 mg Fe per gram dry weight signals high risk); myocardial T2* MRI — values under 20 ms indicate myocardial iron, under 10 ms severe loading with heart-failure risk.
- Deferoxamine: subcutaneous infusion over 8-12 hours, 5-7 nights a week, about 40 mg/kg/day; effective but compliance-defining — the price of the first survival gains.
- Deferiprone: oral 75-100 mg/kg/day in three divided doses; best cardiac iron removal; the licensing hazard is agranulocytosis, mandating weekly blood counts and immediate reporting of fever or sore throat.
- Deferasirox: oral once daily, starting 20 mg/kg with titration to 40; monitor creatinine (tubular toxicity), liver enzymes, and audiology-ophthalmology annually.
- Combination therapy: deferoxamine plus deferiprone for severe myocardial siderosis (T2 under 10-20 ms) improves cardiac T2 faster than either alone.
- Venesection, not chelation, for haemochromatosis: HFE C282Y homozygotes are depleted by phlebotomy (target ferritin around 50-100 µg/L); chelation is for transfusional and dyserythropoietic overload where venesection worsens anaemia.
A typical exam case
A 16-year-old with thalassaemia major on a regular transfusion programme since age two presents with new exertional dyspnoea. Ferritin is 4200 µg/L, liver iron concentration 12 mg/g dry weight, and myocardial T2 is 14 ms — iron in the heart, not just the liver. The reasoning: ferritin tracks total load but correlates poorly with cardiac iron; T2 is the organ-specific verdict. Management escalates to combination chelation (deferiprone daily plus nocturnal deferoxamine infusions), screens cardiac function with echo and arrhythmia monitoring, checks the endocrine axis — short stature, delayed puberty, hypothyroidism, diabetes and hypogonadism follow the same iron deposition — and revisits transfusion strategy to hold pre-transfusion haemoglobin around 90-100 g/L without unnecessary units. T2* is repeated at 6-12 month intervals to document cardiac clearance.
The Indian frame matters here: an estimated ten to fifteen thousand thalassaemia major births occur yearly in India, and access to MRI T2* and newer chelators is uneven, so many programmes still titrate on ferritin trends — examiners from Indian settings expect both the ideal algorithm and its pragmatic substitute.
Where students slip
Matching drug to toxicity is the reliable one-mark discriminator: agranulocytosis means deferiprone, renal tubular injury means deferasirox, deferoxamine carries ototoxicity, retinal toxicity and the skeletal/yersinia quirks of aluminium-era dialysis lore. Second, candidates quote ferritin alone as the cardiac gauge — the T2* value under 20 ms is the number that predicts death from iron cardiomyopathy, and ferritin is an acute-phase reactant besides. Finally, remember that iron and infection travel together: siderophore-armed organisms (Yersinia enterocolitica, Vibrio vulnificus, Klebsiella in the iron-loaded) flourish on non-transferrin-bound iron, so fever in a chelated thalassaemic deserves swift cultures and, classically, deferoxamine cessation during suspected yersinia sepsis.
Frequently asked questions
When should iron chelation begin in thalassaemia major?
After 10-20 transfusions or when serum ferritin persists above about 1000 µg/L, usually around two to three years of age, before cardiac iron accumulates.
Which investigation best quantifies myocardial iron?
Cardiac MRI T2* — values below 20 ms indicate myocardial siderosis and below 10 ms severe loading with imminent heart-failure risk; serum ferritin correlates poorly with cardiac iron.
What is the distinctive toxicity of deferiprone?
Agranulocytosis, which is why weekly blood counts are mandatory and any fever with mouth ulcers demands an urgent count and drug cessation.
Which chelator removes cardiac iron most effectively?
Oral deferiprone has the strongest record of myocardial iron clearance, and combination with deferoxamine is used for severe cardiac loading.
How is hereditary haemochromatosis treated differently?
By serial venesection targeting ferritin around 50-100 µg/L, because the marrow is normal and iron is removed at the source; chelation is reserved for those who cannot tolerate phlebotomy or have transfusional overload.