Insidious Renal Damage in Patients with Thalassemia Major: Is it More Serious than Appreciated?

Abstract

Aim: To investigate early renal injury in thalassemia major patients by using novel serum markers and demonstrate the factors leading to renal injury. Material and Methods: Seventy-one thalassemia major patients (37 males) who were on regular transfusion and chelation programme with deferasirox have been enrolled in this study. Thirty-five healthy children of the same age served as a control group. Serum urea-creatinine, electrolytes, cystatin C and glomerular filtration rate were all noted in our cohort and compared with the control group. Proteinuria was also investigated by calculating UPr/UCr ratio. Results: The median serum creatinine level was 0.4 mg/dL (range; 0.2-0.76 mg/dL) and the median glomerular filtration rate level was 192 mL/min/1.73 m 2 (range; 106-308 mL/min/1.73 m 2) in patients. More than half of the patients had glomerular hyperfiltration (n=48, 67.6%). Hyperfiltration was prominent in thalassemia group (66.2% vs. 19.4%) (p=0.0001). Mean serum cystatin C levels were found to be statistically elevated in patient group comparing with controls (p=0.0001). Serum cystatin C level was above >1 mg/L in 46 patients (64.7%) whereas only three in controls (p=0.0001). Sex, age, hemoglobin level and cardiac T2* MRI results were not related to the elevated cystatin C levels. On the other hand, liver iron burden and serum ferritin levels were noted to be statistically correlated to elevated cystatin C level (p=0.024 and p=0.04). Deferasirox dose below 25 mg/kg/day was also found in relation with elevated cystatin C levels. Conclusion: Renal injury is multifactorial, insidious but progressive in thalassemia patients. High index of suspicion and routine use of novel markers are required for detection of renal injury during the follow up of thalassemia patients.