The objective of this study was to investigate renal function in a cohort of 98 patients with sickle cell disease (SCD) followed up at a tertiary hospital in Brazil. Clinical and laboratory characteristics at the time of the most recent medical examination were analyzed. Renal function was evaluated by the estimation of glomerular filtration rate (GFR) by the criteria of the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI). We compared patients with normal GFR to patients with decreased GFR (<60 mL·min−1·(1.73 m2)−1) and hyperfiltration (>120 mL·min−1·(1.73 m2)−1). Comparison between patients according to the use of hydroxyurea and comparison of clinical and laboratory parameters according to GFR were also carried out. Average patient age was 33.8 ± 13.3 years (range 19-67 years), and 57 (58.1%) patients were females. The comparison of patients according to GFR showed that patients with decreased GFR (<60 mL·min−1·(1.73 m2)−1) were older, had lower levels of hematocrit, hemoglobin and platelets and higher levels of urea and creatinine. Independent risk factors for decreased GFR were advanced age (OR = 21.6, P < 0.0001) and anemia (OR = 39.6, P < 0.0001). Patients with glomerular hyperfiltration tended to be younger, had higher levels of hematocrit, hemoglobin and platelets and lower levels of urea and creatinine, with less frequent urinary abnormalities. Hydroxyurea, at the dosage of 500-1000 mg/day, was being administered to 28.5% of the patients, and there was no significant difference regarding renal function between the two groups. Further studies are required to establish the best therapeutic approach to renal abnormalities in SCD.

SCD is associated with important renal abnormalities. Hydroxycarbamide seems to protect kidney function in SCD by decreasing proteinuria but not microalbuminuria.

Background/Aims: Kidney abnormalities are one of the main chronic complications of sickle cell disease (SCD). The aim of this study is to investigate the occurrence of renal tubular abnormalities among patients with SCD. Methods: This is a prospective study with 26 SCD adult patients in Brazil. Urinary acidification and concentration tests were performed using calcium chloride (CaCl₂), after a 12h period of water and food deprivation. Fractional excretion of sodium (FE_Na), transtubular potassium gradient (TTKG) and solute free water reabsorption (TcH₂O) were calculated. The SCD group was compared to a group of 15 healthy volunteers (control group). Results: Patient`s average age and gender were similar to controls. Urinary acidification deficit was found in 10 SCD patients (38.4%), who presented urinary pH >5.3 after CaCl₂ test. Urinary osmolality was significantly lower in SCD patients (355±60 vs. 818±202mOsm/kg, p=0.0001, after 12h period water deprivation). Urinary concentration deficit was found in all SCD patients (100%). FE_Na was higher among SCD patients (0.75±0.3 vs. 0.55±0.2%, p=0.02). The TTKG was higher in SCD patients (5.5±2.5 vs. 3.0±1.5, p=0.001), and TcH₂O was lower (0.22±0.3 vs. 1.1±0.3L/day, p=0.0001). Conclusions: SCD is associated with important kidney dysfunction. The main abnormalities found were urinary concentrating and incomplete distal acidification defect. There was also an increase in the potassium transport and decrease in water reabsorption, evidencing the occurrence of distal tubular dysfunction.

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