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Abstract: PO2298

Measurement of GFR and Vasoactive Substances in Children with Sickle Cell Anemia

Session Information

Category: Pediatric Nephrology

  • 1700 Pediatric Nephrology

Authors

  • Ejike, Oluwadamilola, Baylor Medical Center, San Antonio, Texas, United States
  • Schwartz, George J., University of Rochester Medical Center, Rochester, New York, United States
  • Legan, Susan, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States
  • Becker, Amy M., Driscoll Children's Hospital, Corpus Christi, Texas, United States
  • Quigley, Raymond P., University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States
Background

Patients with sickle cell anemia (SCA) have a high risk of developing renal disease. Sickle cell nephropathy is thought to begin in childhood with higher than normal glomerular filtration rates (GFRs) known as hyperfiltration that can lead to proteinuria, sclerosis of the glomeruli, decreased GFR, and eventual renal failure. This model of sickle cell nephropathy has not been validated in clinical studies. This study measured directly the GFRs of patients with sickle cell anemia and age matched control patients. In addition, urinary vasoactive substances were measured to correlate with the GFR.

Methods

Children with sickle cell anemia (SCA) and sickle-β0-thalassemia (HbSb0) were recruited for the study from the Sickle Cell Clinic at Children’s Medical Center of Dallas. These sickle cell disease genotypes are phenotypically similar and are the most severe. Healthy siblings of children seen in the Pediatric Nephrology Clinic at Children’s Medical Center of Dallas were recruited to serve as controls.
GFR was measured directly from iohexol clearance. Urine was obtained to measure vasoactive substances.

Results

Subjects: SCA:32 and Control:13
The GFR of the sickle cell group was 148 ± 36 ml/min/1.73 m2 (Mean and SD) and the control group was 130 ± 17 ml/min/1.73 m2. The p-value (un-paired t-test) is 0.089 and thus is not statistically significant.
However, the SCA group had 21/32 with a GFR 〉130 while the control group had only 3/13 (p=0.019). Thus, there were more patients in the SCA group with hyperfiltration. There was no difference in urinary cGMP or PGE2. However, PGF2α was higher in the control group.
Surprisingly, the urinary angiotensinogen (factored for urinary creatinine) was lower in the SCA group than in the controls (see table).

Conclusion

In conclusion, we have shown that although the GFR in patients with SCA might not be elevated, there appears to be a population of SCA patients with higher than normal GFR. The intrarenal renin-angiotensin system appears to play a role in this hyperfiltration. Further studies are needed to continue to understand this phenomenon.

Urine Angiotensinogen / urine creatinine
 MeanSD
HbSS8.06.5
Control14.68.3

HbSS urine angiotensinogen/creatinine was significantly lower than control (p<0.005).