Magnetic resonance detection of kidney iron deposition in sickle cell disease: a marker of chronic hemolysis.
OBJECTIVE
To study the pattern, etiology, and significance of renal iron accumulation in chronically transfused sickle cell disease (SCD) and thalassemia major (TM) patients using magnetic resonance imaging (MRI).


METHODS
Magnetic resonance imaging (MRI) was performed in 75 SCD patients, 73 TM patients, and 16 healthy controls. Multiecho gradient echo protocols were used to measure T2* reciprocals (R2*) in the kidney, liver, and heart. Kidney R2* was compared to tissue iron estimates, serum iron markers, and surrogates of intravascular hemolysis by univariate regression.


RESULTS
Mean R2* in SCD patients was 55.3+/-45.3 Hz, compared with 22.1+/-11 Hz in TM patients and 21.3+/-5.8 Hz in control subjects (P<0.001). Kidney R2* decreased with advancing age (R2=0.09, P<0.02). Kidney R2* correlated strongly with increased serum lactate dehydrogenase levels found in SCD (R2=0.55, P<0.001), but was independent of hepatic iron concentration and cardiac R2*. Kidney R2* did not correlate with blood pressure, creatinine, cardiac index, or right and left ejection fraction.


CONCLUSIONS
Intravascular hemolysis, not chronic transfusion, causes renal hemosiderosis in SCD. Prospective trials are necessary to determine whether kidney R2* is a biomarker for hemolysis-mediated vascular complications in SCD.
Schein
Aaron
A
Department of Diagnostic Radiology, Keck School of Medicine, University of Southern California, Los Angeles, California 90027, USA.
Enriquez
Cathleen
C
Coates
Thomas D
TD
Wood
John C
JC
D000293:Adolescent; D000465:Algorithms; D000743:Anemia, Hemolytic / Q000175:diagnosis* / Q000378:metabolism*; D000755:Anemia, Sickle Cell / Q000175:diagnosis* / Q000378:metabolism*; D015415:Biomarkers / Q000032:analysis; D002908:Chronic Disease; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D007501:Iron / Q000032:analysis*; D019190:Iron Overload / Q000175:diagnosis* / Q000378:metabolism*; D007668:Kidney / Q000737:chemistry; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
D015415:Biomarkers; D007501:Iron
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