الفهرس 
THALASSEMIA
Management of complicationOnly 14 pages are availabe for public view
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Abstract
Background: β-thalassemia major (β-TM) is an inherited disease resulting from reduction or total lack of β-globin chains. Repeated blood transfusions are inevitably associated with iron overload that leads to multiple organ dysfunctions namely heart, liver and endocrine glands. Some published studies demonstrated proteinuria, aminoaciduria, low urine osmolarity, and excess secretion of the proximal tubule damage markers in pediatric patients with thalassemia. Magnetic resonance imaging (MRI) gradient echo (T2*), the reciprocal of T2* (known as R*), has been developed to quantify tissue iron in the liver, the heart as well as the kidneys. Aim: To assess tissue iron overload by MRI among transfusion dependent β-thalassemia patients and its relation to levels of urinary albumin excretion and serum cystatin C as markers of renal functions. Methods: Fifty β-TM patients were compared to 25 healthy controls and studied stressing on splenectomy, transfusion history, chelation therapy and serum ferritin. Urinary albumin excretion (UAE) was assessed in an early morning fasting urine sample as albumin-to-creatinine ratio (UACR) to detect micro- or macro-albuminuria. Serum levels of cystatin C were measured by enzyme linked immunosorbent assay. Magnetic resonance imaging including the parameter R2 was used to measure iron content in tissues using a multiecho-gradient echo technique. Results: Serum cystatin C and UACR were significantly higher in β-TM patients than the control group. When the studied parameters of renal function were compared among patients with mean serum ferritin above or lower than 2500 µg/L, significantly higher serum cystatin C and UACR were found to be associated with high ferritin cutoff. Significant positive correlations were found between serum cystatin C and total and indirect bilirubin, LDH, serum ferritin and uric acid. Serum cystatin C was positively correlated to renal R2* while negatively correlated to renal T2*. Multivariable linear regression analysis revealed that indirect bilirubin, LDH, serum ferritin, renal T2* and renal R2* were the significant independent variables related to increased cystatin C levels in patients with β-TM. Liver T2* was significantly lower with higher liver R2* and LIC among patients with serum ferritin ≥2500 µg/L and those with poor compliance to chelation therapy. Renal R2* and cardiac R2* were also associated with poor compliance. Correlation studies with respect to MRI parameters revealed significant positive correlations between liver T2* and cardiac T2* as well as renal T2* while liver T2* was negatively correlated with serum ferritin, cardiac R2*, cardiac MIC, renal R2* and renal iron concentration. Conclusion: We suggest that glomerular and tubular dysfunctions are common in pediatric patients with β-TM and are related to tissue iron overload and poor compliance to chelation. Further prospective studies are needed to verify these results and examine the effect of chelating agents on renal structural and functional integrity among β-TM patients.
Keywords: Kidney Iron Deposition; β-thalassemia