1. ¹Thalassemia Center, Laikon General Hospital, Athens, Greece
2. ²Department of Medical Research, 251 General Airforce Hospital, Athens, Greece
3. ³Department of Nephrology, Laikon General Hospital, Athens, Greece
4. ⁴Department of Clinical Biochemistry, 'Aghia Sophia' Children's Hospital, Athens, Greece
5. ⁵Department of Clinical Therapeutics, University of Athens School of Medicine, Athens, Greece
6. ⁶Foundation for Biomedical Research of the Academy of Athens, Athens, Greece

Correspondence: E Voskaridou, Thalassemia Center, Laikon General Hospital, 16 Sevastoupoleos street, GR-11526, Athens, Greece. E-mail: ersi_voskaridou@yahoo.com

Received 23 September 2005; Revised 5 December 2005; Accepted 3 January 2006; Published online 22 February 2006.

Abstract

Progressive renal failure is one of the main complications in HbS/-thalassemia (HbS/-thal). Early identification of patients at high risk of developing renal failure is of great importance as it may allow specific measures to delay the progression of renal damage and thus reduce the incidence of end-stage renal failure and mortality. Early predictors of renal impairment in HbS/-thal remain to explore. Within this context, we studied 87 compound HbS/-thal patients (36 males/51 females; median age 39 years) and 30 healthy controls. In addition to conventional renal biochemistries we measured serum cystatin-C (Cys-C), urine N-acetyl--D-glucosaminidase (NAG) excretion and serum and urinary ₂-microglobulin (₂-M). Cystatin-C, NAG and serum ₂-M levels were higher in patients than controls. The incidence of patients with high levels of Cys-C, NAG, and ₂-M was 32.1, 74.7, and 70.1% respectively, while only 6.8% of patients had increased serum creatinine levels. Cystatin-C and serum ₂-M showed a strong correlation with creatinine clearance and age, while NAG positively correlated with proteinuria. An inverse correlation was also shown between hemoglobin and ₂-M, NAG, and Cys-C levels. Seven patients with proteinuria received therapy with angiotensin-converting enzyme (ACE) inhibitors. Changes of poteinuria positively correlated with NAG levels. These results indicate that Cys-C is an accurate marker of renal dysfunction, and urinary NAG excretion can be considered as a reliable index of the tubular toxicity, and possible predictor of proteinuria and eventual renal impairment in HbS/-thal patients. Furthermore, NAG measurement may be used for monitoring ACE-inhibitors therapy in HbS/-thal patients with proteinuria.