Abstract
The relationship between pancreatic iron overload and glucose dysregulation has not been well defined and need further investigation. Pancreas iron load measurements are also necessary to understand how hepatic, pancreatic, and cardiac iron burden prospectively modulate the evolution of diabetes in transfusion dependent thalassemia (TDT).
Aim: This study aims to evaluate the presence of pancreatic iron overload among TDT patients in Turkey based on the MRI R2* and T2* results as well as to determine its association to Fasting blood glucose (FBG), insulin, fructosamine, Homa-IR, C-peptide, ferritin, liver, cardiac and hypophysis MRI R2* results.
Material and Methods: This study was conducted at the Thalassemia Center in Istanbul University, Istanbul Medical Faculty. Forty-one TDT patients included the study with a mean age of 29.9±9,9 (median 29) years old, ranging from 11 to 45 years old. Pancreatic, liver, cardiac and hypophsis MRI's were conducted using 1.5 Tesla Philips MRI machine in the Department of Radiology.
Pancreatic MRI R2* results < 30 Hz were considered normal, 30-100 Hz as mild, and > 100 Hz as moderate to severe pancreatic siderosis. Pancreatic MRI T2 results >26 ms were is normal, < 10 ms is severe iron overload as presented at literature. Correlations between pancreatic MRI R2* results and FBG, insulin, fructosamine, Homa-IR, C-peptide, ferritin, cardiac and hypophysis MRI R2* were evaluated using the Pearson correlation, Man Whitney U test.
Results: Laboratory findings of glucose metabolism and MRI's of liver, pancreas, hypophsis and cardiac iron are shown at Table 1. There were no significant relationship between fasting blood glucose, insülin, C-peptid level, fructosamine, Homa-IR, ferritin and Pancreas T2* and R2* results (p>0.05). There was significant correlation between liver and pancreas MRI T2* and R2* results. (p<0.01). There was no significant correlation between hypophysis global R2, cardiac R2*, Pancreas T2* and, Pancreas R2* measurements (p>0.05). Fourteen patients were found to have normal pancreatic MRI R2* (34,1%) while 19 patients have normal pancreatic MRI T2 (46.3%). It is reported that T2 is irrelevant to age and sex, and R2 can be related to age-related fatty degeneration.
There was significant pancreatic iron burden in 31.7% of patients (R2*>100 Hz), of whom only 1 patient was under 18 years of age.There were 22 (53.6%) patients with T2* <26 ms and had iron overload, 13 (31.7%) had T2 <10 ms and had significant iron overload. Almost three-quarters of patients (n:13, 31.7%) had moderate to severe pancreatic iron load on both T2* and R2* measurements. Thirteen patients with significant pancreatic iron overload had 3 severe hypophysis, 1 moderate, 2 severe cardiac siderosis. and had no serious liver iron burden. This shows that the treatment of chelation first led to liver, then heart and pituitary, respectively, and finally pancreatic iron burden and demonstrates the importance of pancreas MR in assessing the body iron load.
Discussion:The lack of correlation between pancreatic and cardiac MRI R2* are in contrast to another demonstrating that pancreatic iron load are good predictors of cardiac iron load. This is due to the fact that our patients are followed up with cardiac MR and taken to the intensive chelation programs of the patients who detect iron in the heart.
Previous studies also report that while pancreatic R2* may be sensitive for glucose dysregulation, most patients may still have no symptoms and normal blood glucose, indicating the presence of a preclinical iron burden. Pancreatic MRI R2* can detect pancreatic iron accumulation at a much earlier stage. Lack of excessive iron load in liver of our patient can be explain low glucose metabolism disorder despite high pancreatic iron overload.
No relevant conflicts of interest to declare.
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