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Diabetes mellitus and cardiomyopathy are common in chronically transfused thalassemia major patients, occurring in the second and third decades of life. We postulated that pancreatic iron deposition would precede cardiac iron loading, representing an environment favorable for extrahepatic iron deposition. To test this hypothesis, we examined pancreatic and cardiac iron in 131 thalassemia major patients over a 4-year period. Cardiac iron (R2* > 50 Hz) was detected in 37.7% of patients and pancreatic iron (R2* > 28 Hz) in 80.4% of patients. Pancreatic and cardiac R2* were correlated (r(2) = 0.52), with significant pancreatic iron occurring nearly a decade earlier than cardiac iron. A pancreatic R2* less than 100 Hz was a powerful negative predictor of cardiac iron, and pancreatic R2* more than 100 Hz had a positive predictive value of more than 60%. In serial analysis, changes in cardiac iron were correlated with changes in pancreatic iron (r(2) = 0.33, P < .001), but not liver iron (r(2) = 0.025, P = .25). As a result, pancreatic R2* measurements offer important early recognition of physiologic conditions suitable for future cardiac iron deposition and complementary information to liver and cardiac iron during chelation therapy. Staging abdominal and cardiac magnetic resonance imaging examinations could significantly reduce costs, magnet time, and need for sedation in young patients.

Iron endocrinopathy and cardiomyopathy are common in chronically transfused thalassaemia major patients, but relatively rare in chronically transfused patients with sickle cell disease. Since magnetic resonance imaging can demonstrate preclinical organ iron deposition, we hypothesized that pancreas and cardiac R2* would likewise be lower in sickle cell disease patients than thalassaemia major patients having comparable transfusional burdens. To test this hypothesis, we examined pancreatic and cardiac iron in a convenience sample of 100 chronically-transfused sickle cell disease and 131 thalassaemia major patients. Cardiac R2* (30 ± 9·2 vs. 73 ± 53 Hz, P < 0·0001) and pancreatic R2* (52 ± 62 vs. 253 ± 224 Hz, P < 0·0001) were significantly lower in sickle cell disease than thalassaemia major. Liver iron concentration was similar in both groups (14·9 ± 9·8 vs. 12·3 ± 8·4 mg/g dry weight, P = 0·101). The observed disparity in pancreatic and cardiac iron loading between sickle cell disease and thalassaemia major patients mirrors prior observations of organ toxicity in these patients. Greater cumulative transfusional iron exposure in thalassaemia major patients partially explains these observations but our data also suggest innate differences in labile iron handling between the two diseases. [ABSTRACT FROM AUTHOR]