51Cr-EDTA measurements of the glomerular filtration rate in patients with sickle cell anaemia and minor renal damage.
BACKGROUND
Creatinine clearance has been reported to be inaccurate for the estimation of glomerular filtration rate (GFR) in patients with sickle cell anaemia (SCA). Inulin clearance, the reference method for GFR estimation, is impractical for routine use in these patients, and 51Cr-EDTA measurements of the GFR have been rarely reported in this disease.


METHODS
In order to obtain reference 51Cr-EDTA values in this disease, we studied 70 patients (40 females; 13-59 years of age, mean: 31.6 years) with homozygous SCA, normal serum creatinine and urinary albumin excretion < or =200 microg x min(-1). All patients were submitted to single-injection 51Cr-EDTA GFR, urinary albumin and haematocrit measurements. 51Cr-EDTA clearances were calculated in different age groups (<20, 20-29, 30-39, 40-49 and >50 years).


RESULTS
The mean GFR (+/-standard deviation) obtained for the 70 patients was 111.5+/-23.1 ml x min(-1). Analysis of variance for evaluation of the possible interaction effect between 51Cr-EDTA clearance and sex, age, urinary albumin and haematocrit demonstrated patient age as the only factor influencing 51Cr-EDTA clearance (P < 0.001). The Spearman correlation coefficient showed a significant relationship between 51Cr-EDTA clearance and patient age (r = -0.44, P = 0.0001), but not between 51Cr-EDTA and urinary albumin (r = -0.17, P = 0.1546) or haematocrit (r = 0.079, P = 0.5121). The group aged 20-29 years presented the highest 51Cr-EDTA clearance mean value (126.7+/-20.4 ml x min(-1)), with a progressive reduction in the older groups.


CONCLUSIONS
Young adults with homozygous SCA, normal serum creatinine and micro-albuminuria or normo-albuminuria present supranormal 51Cr-EDTA GFR values. These values rapidly decrease after 30 years of age. We did not find association between urinary albumin and GFR in these patients.
Barros
Fabiana B
FB
Nuclear Medicine Division, Department of Radiology, State University of Campinas, Brazil.
Lima
Carmen S P
CS
Santos
Allan O
AO
Mazo-Ruiz
Mariana F C
MF
Lima
Mariana C L
MC
Etchebehere
Elba C S C
EC
Costa
Fernando F
FF
Saad
Sara T O
ST
Camargo
Edwaldo E
EE
Ramos
Celso D
CD
D000293:Adolescent; D000328:Adult; D000755:Anemia, Sickle Cell / Q000150:complications / Q000000981:diagnostic imaging*; D002860:Chromium Radioisotopes; D004492:Edetic Acid; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007674:Kidney Diseases / Q000000981:diagnostic imaging* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D011866:Radioisotope Renography / Q000379:methods*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D002860:Chromium Radioisotopes; D019275:Radiopharmaceuticals; D004492:Edetic Acid