Renal function in transfusion-dependent pediatric beta-thalassemia major patients.

PURPOSE: In this study, the relationship between glomerular and tubular function and creatinine, glomerular filtration rate (GFR) and urine NAG in thalassemia major patients aged 7-16 years was investigated. DESIGN AND SETTING: This is a case-control study comprising 280 individuals [144 (51·4%), males; 136 (48·6%), females]. MATERIALS AND METHODS: Patients were divided in groups of 14 individuals and age groups of 7-16 years. Sodium excretion fraction, fraction excretion of potassium, calcium-to-creatinine and uric acid-to-creatinine ratios, and duration of specific blood transfusion were determined in all age groups receiving deferoxamine. RESULTS: GFR decreased with increasing age, but the correlation was not statistically significant. There was no significant correlation between the ferritin levels and the GFR changes. The mean value of NAG activity between thalassemic patients and controls has no significant difference. The difference in mean age of the groups with high NAG activity and normal NAG activity was statistically significant. Thirty-seven patients (52·1%) in the group with normal NAG activity, and 45 patients (6·25%) in the group with NAG activity above normal were observed with uricosuric effects with no significant difference. Four patients (6·9%) in the group with normal NAG activity and six patients (7·3%) in the group with NAG activity above normal were shown to have hematuria with no significant difference. The results show that the increase in serum ferritin is significantly correlated with the increase in NAG activity (P<0·001, r = 0·2). Of patients with normal NAG activity 1 (1·7%) and with NAG activity higher than normal, 13 (15·9%) cases experienced hypercalciuria that significant difference was existing. The data also indicated that the NAG changes do not correlate with GFR changes. CONCLUSION: The results showed that kidney dysfunction in thalassemia increases with increasing age, duration, and levels of blood transfusion and hypercalciuria. It is therefore recommended that the presence of severe renal dysfunction in thalassemic patients should be investigated using sensitive and specific tests, mainly NAG, to prevent progress towards the complications.

Renal tubular dysfunction in pediatric patients with beta-thalassemia major.

To evaluate the prevalence of renal tubular dysfunction in children with ß-thalassemia (ß-T) major, we studied the glomerular and tubular function in 140 children with ß-T major and compared them to a healthy control group at our center from May 2007 to April 2008. Fresh first morning samples were collected from each patient and analyzed for sodium, potassium, calcium (Ca), protein, uric acid (UA), creatinine (Cr), urine osmolality and urinary N-acetyl-ß-D-glucosaminidase (UNAG) activity. Blood samples were also collected for complete blood count, blood urea nitrogen (BUN), fasting blood sugar, serum creatinine (SCr), electrolytes, and ferritin before transfusion. Among the study patients, 72 were males, and the mean age was 11.5 (ranging 7-16) years. SCr levels were all within normal limits and all of them had normal glomerular filtration rate (GFR). The mean UNAG was 17.8 IU/L in the study patients (normal 0.15-11.5 IU/L) and 3.2 IU/L in the control group (P < 0.001). Of the 82 study patients who had elevated level of UNAG, 58 (62.4%) had high blood levels of ferritin also (r = 0.2, P < 0.001) and 13 (15.9%) patients had hypercalciuria also (UCa/UCr > 0.21) (P = 0.006). Nine (6.4%) thalassemic patients with a mean age of 12 years had proteinuria (Upr/UCr > 0.2). Sixty-nine (49.3%) out of the 140 patients and 45 (65.2%) of the patients having UNAG had uricosuria also (UUA/UCr > 0.26). Ten (7%) patients had microscopic hematuria and 10 (7%) patients with a mean age of 13.5 years had glucosuria or diabetes mellitus. We conclude that tubular dysfunction is a relative common complication of the ß-T major; UNAG and its index are the best to detect renal tubular dysfunction in these patients. Currently, periodic measurement of UCa/UCr and UUA/UCr ratios as well as urinalysis are recommended.