Renal function in children with beta-thalassemia major and thalassemia intermedia

Renal functions in pediatric patients with beta-thalassemia major: relation to chelation therapy: original prospective study

BACKGROUND

In beta-thalassemia, profound anemia and severe hemosiderosis cause functional and physiological abnormalities in various organ systems. In recent years, there have been few published studies mainly in adult demonstrating renal involvement in beta-thalassemia. This prospective study was aimed to investigate renal involvement in pediatric patients with transfusion dependent beta-thalassemia major (TD-betaTM), using both conventional and early markers of glomerular and tubular dysfunctions, and to correlate findings to oxidative stress and iron chelation therapy.

METHODS

Sixty-nine TD-betaTM patients (aged 1-16 years) and 15 healthy controls (aged 3-14 years) were enrolled in this study. Based on receiving chelation therapy (deferoxamine, DFO), patients were divided into two groups: group [I] with chelation (n=34) and group [II] without chelation (n=35). Levels of creatinine (Cr), calcium (Ca), inorganic phosphorus (PO4), uric acid (UA) and albumin were measured by spectrophotometer. Serum (S) levels of cystatin-C (SCysC) and total antioxidant capacity (STAC) and urinary (U) levels of beta2-microglobulin (Ubeta2MG) were measured by immunosorbent assay (ELISA). Urinary N-acetyl-beta-D-glucosaminidase (UNAG) activity and malondialdehyde (UMDA) were measured by chemical methods. Estimated glomerular filtration rate (eGFR) was determined from serum creatinine.

RESULTS

In patient with and without chelation, glomerular [elevated SCysC, SCr, Ualbumin/Cr and diminished eGFR]; and tubular dysfunctions [elevated SUA, SPO4, UNAG/Cr, Ubeta2MG/Cr] and oxidative stress marker disturbances [diminished STAC and elevated UMDA/Cr] were reported than controls. In patients with chelation, SCysC was significantly higher while, STAC was significantly lower than those without chelation. In all patients, SCysC showed significant positive correlation with SCr and negative correlation with eGFR; STAC showed significant positive correlation with eGFR and negative correlation with SCysC, SCr, UNAG/Cr; UMDA/Cr showed significant positive correlation with Ualbumin/Cr, Ubeta2MG/Cr, UNAG/Cr.

CONCLUSIONS

Our data confirm high frequency of glomerular and tubular dysfunctions in TD-betaTM pediatric patients which could be attributed to oxidative stress and DFO therapy.

Differences in the prevalence of growth, endocrine and vitamin D abnormalities among the various thalassaemia syndromes in North America

This study aimed to determine differences in the rates of growth, endocrine- and calcium-related abnormalities in the various thalassemia syndromes in North America treated with current therapies. Medical history, physical examinations and blood and urine collections were obtained from patients with all thalassemia syndromes age 6 years and older in the Thalassemia Clinical Research Network. 361 subjects, 49% male, mean age 23.2 years (range 6.1-75 years) were studied. Approximately 25% of children and adults, regardless of the thalassemia syndrome, had short stature. Overall growth in children was mildly affected. Final height was close to midparental height (z = -0.73 +/- 1.24). Patients with beta thalassemia major (TM) had higher rates of hypogonadism, multiple endocrinopathies, worse hyperglycaemia, subclinical hypoparathyroidism and hypercalciuria. Hypogonadism remained the most frequent endocrinopathy and was frequently under-treated. 12.8% of the subjects had 25 vitamin D concentrations less than 27 nmol/l and 82% less than 75 nmol/l, regardless of the thalassemia syndrome. Adolescents had lower 25 vitamin D levels than children and adults. Compared to patients with other thalassemia syndromes, those with beta TM suffered from higher rates of multiple endocrinopathies, abnormal calcium metabolism and hypercalciuria. Vitamin D abnormalities were high among adolescents.