GFR in Patients with β-Thalassemia Major

Detection of Renal Insufficiency in a Cohort of Patients With Beta-thalassemia Major Using Cystatin-C

With increased life expectancy among patients with beta-thalassemia major (β-TM) renal insufficiency has been frequently noted because of the persistence of anemia, iron overload and some drug side effects. Serum creatinine becomes elevated in late stage of kidney affection. Cystatin-C is more sensitive biomarker for kidney dysfunction. Our aim was to measure Cystatin-C serum level among patients with β-TM as a marker of early nephropathy. Serum Cystatin-C was measured in 94 patients with β-TM using Enzyme-Linked Immunosorbent Assay (ELISA) and correlated to other clinical, laboratory and radiologic data. Glomerular hyperfiltration was observed in 30.8% while Cystatin-C was elevated in 56.3% of β-TM. Patients having high serum Cystatin-C were older in age and having higher serum levels of aspartate aminotransferases and urea. Cystatin-C level was positively correlated with serum creatinine and urea and negatively correlated with glomerular filtration rate. Periodic assessment of Cystatin-C in patients with β-TM is recommended for early diagnosis of renal dysfunction especially during drug dosing prescription aiming to obtain the maximum effectiveness and safety. Controlling anemia by maintaining appropriate hemoglobin level with close monitoring of iron overload are also recommended to preserve renal function among β-TM patients.

Beta-thalassemia: renal complications and mechanisms: a narrative review

OBJECTIVES

Beta-thalassemias are a group of recessively autosomal inherited disorders of hemoglobin synthesis, which, due to mutations of the beta-globin gene, lead to various degrees of defective beta-chain production, an imbalance in alpha/beta-globin chain synthesis, ineffective erythropoiesis, and anemia. Improved survival in thalassemic patients has led to the emergence of previously unrecognized complications, such as renal disease.

METHODS

A comprehensive literature review through PubMed was undertaken to summarize the published evidence on the epidemiology and pathophysiology of renal disease in thalassemia. Literature sources published in English since 1990 were searched, using the terms beta-thalassemia, renal disease.

RESULTS

Renal disease is considered to be the 4th cause of morbidity among patients with transfusion dependent thalassemia. Chronic anemia, hypoxia and iron overload are the main mechanisms implicated in development of renal injury, whereas several studies also suggested a contributive role of iron chelators.

DISCUSSION AND CONCLUSION

Kidney disease may develop through progressive renal tubular and glomerular damage; thus, its early recognition is important in order to prevent and/or reverse deterioration. This review will provide an insight on the involved mechanisms implicated in kidney disease in thalassemic patients and will discuss the updates on diagnosis and prevention of renal complications in thalassemia.

Renal complications in thalassemia

Thalassemia is a disease with an extensive morbidity profile affecting almost every organ system. Renal involvement, once considered rare, is an underestimated and poorly studied complication that has been on the rise ever since medical advances granted patients longer life spans. Several studies and reports have emerged recently to shed light on the seriousness of this complication, although data is still lacking in terms of pathophysiology, diagnosis, prevention and treatment. In this review, we evaluate and compare renal involvement in the transfusion-dependent and independent variants of β-Thalassemia, highlighting the pathophysiology of kidney damage that involves iron overload, chronic anemia, and iron chelation therapy. An in-depth and focused review of the types of injuries incurred is also presented along with the diagnostic biomarkers accompanying each type of injury. Most research so far has focused on the transfusion-dependent thalassemia population being the group with most renal involvement, however recent reports have shown evidence of comparable, if not worse, involvement of the non-transfusion dependent population, sometimes leading to end-stage renal disease. As such, we try to shed light on distinct renal involvements in NTDT whenever available.

Renal Hemosiderosis among Iranian Transfusion Dependent β-Thalassemia Major Patients

Background: In recent years, the success in management of thalassemic patients, has allowed for some previously unrecognized complications including renal abnormalities to emerge. This prospective study aimed to investigate kidney iron overload by means of MRI T2* and also renal function based on laboratory tests for early markers of glomerular and tubular dysfunction among adult Iranian transfusion-dependent thalassemia major patients. Subjects and Methods: Two-hundred and two patients with transfusion-dependent β-thalassemia major were included in this study in Zafar Adult Thalassemia Center, Tehran, Iran. For all patients, kidney MRI T2* as well as evaluation of BUN, creatinine, uric acid, calcium, phosphorus, sodium (Na), potassium (K), total protein, albumin, cystatin C, serum ferritin β2-microglobulin, NAG (N-acetyl-beta-D-Glucosaminidase), and urine protein were performed. Results: One-hundred and fourteen female and 88 male transfusion-dependent β-thalassemia major patients with mean age of 30.1 ± 9.4 participated in the present study. We found that 77.7% of our patients had kidney hemosiderosis based on MRI T2*. Also, 67 patients (33.2%) had elevation of serum cystatin C, and 104 patients (51.5%) had reduced estimated glomerular filtration rate (e-GFR). Increased urinary excretion of NAG and hypercalciuria were found in 50% and 79.2% of participants, respectively. Conclusion: Renal hemosiderosis and asymptomatic renal dysfunction are prevalent among transfusion- dependent β-thalassemia major patients which necessitate regular screening with early markers of glomerular and tubular dysfunction. Further studies in order to investigate the correlation between renal hemosiderosis and early markers of kidney dysfunction among these patients are recommended.