Short-term follow-up of patients with sickle cell disease and albuminuria

Background. Albuminuria with normal serum creatinine occurs frequently in patients with sickle cell disease (SCD), but the rate of progression to more advanced chronic renal disease is unknown. The purpose of this study was to investigate the rate of progression of children and young adults with SCD and albuminuria over time. Procedure. Urine albumin/creatinine (A/C) ratios and serum creatinine were obtained serially. Serum cystatin C levels were determined in a subgroup of 20 patients. Results. Of 38 patients with SCD who had albuminuria (30 with microalbuminuria and 8 with proteinuria), 10.5% had progressive disease during follow-up of 20 12 months. Progressive disease was observed in 2 of 30 patients with MA because MA worsened to either intermittent proteinuria (1 patient), or persistent proteinuria after 7 months follow-up (1 patient). Two of eight patients with proteinuria worsened to nephrotic-range after 8 and 17 months with elevations of serum creatinine. All eight patients with proteinuria were treated with angiotensin blockade and/or hydroxyurea. Of those, six patients responded to treatment with decreased albuminuria and no changes in serum creatinine. Serum cystatin C level trended to increase before serum creatinine in patients with proteinuria. Conclusions. Patients with rapid progression to nephrotic-range proteinuria showed decreased kidney function. Therefore, patients with albuminuria should be monitored closely for progression, and therapy with hydroxyurea and/or angiotensin blockade should be considered for patients who develop proteinuria. Serum cystatin C appears more sensitive than serum creatinine to detect early decrease in kidney function.