Chromium-51 ethylenediamine tetraacetic acid glomerular filtration rate: a better predictor than glomerular filtration rate calculated by the Cockcroft-Gault formula for renal involvement in systemic lupus erythematosus patients.
OBJECTIVE
To investigate whether the ethylenediamine tetraacetic acid (EDTA) glomerular filtration rate (GFR) is a better indicator of the degree of renal involvement than serum creatinine concentration or creatinine clearance calculated by the Cockroft-Gault formula.


METHODS
We studied prospectively all systemic lupus erythematosus (SLE) patients with normal or borderline serum creatinine concentration (<110 micromol/l) and urinary sediment abnormalities and/or proteinuria in the last 2 yr. EDTA-GFR, serum creatinine concentration, calculated creatinine clearance (Cockroft-Gault formula) and 24-h urine protein were determined at the same time. Renal biopsies were performed in patients with low values of EDTA-GFR or significant proteinuria.


RESULTS
Twenty-three patients were identified, of whom 22 were females. The average age of the patients was 31.6+/-8.2 yr. Biopsies were assigned to WHO classes as follows: class II, 1 patient; class III, 6 patients; class IV, 10 patients; class V, 6 patients. The average serum creatinine concentration, EDTA-GFR and calculated creatinine clearance were 79.8+/-mol/l, 74.5 ml/min and 97 ml/min respectively. EDTA-GFR showed abnormal values (<80 ml/min) in 15 of the 23 patients (65.2%) while calculated creatinine clearance was abnormal (<80 ml/min) in three of the 23 patients (13%) (P<0.001). Using the Pearson correlation test, we did not find any correlation between EDTA-GFR or creatinine clearance values and the sum of activity and chronicity indices.


CONCLUSIONS
GFR performed by EDTA-GFR correctly predicted renal involvement in SLE patients, whereas GFR calculated by the Cockcroft-Gault formula may have underestimated renal function. Significant numbers of patients with WHO class III, IV or V lupus nephritis may be missed if biochemical creatinine clearance or serum creatinine concentration alone is used to assess renal disease.
Godfrey
T
T
Lupus Research Unit, The Rayne Institute, St Thomas' Hospital, London SE1 7EH, UK.
Cuadrado
M J
MJ
Fofi
C
C
Abbs
I
I
Khamashta
M A
MA
Nunan
T
T
Hughes
G R
GR
D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000652:urine; D002614:Chelating Agents / Q000494:pharmacology*; D003404:Creatinine / Q000097:blood; D004492:Edetic Acid / Q000493:pharmacokinetics*; D005260:Female; D005919:Glomerular Filtration Rate / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D008181:Lupus Nephritis / Q000503:physiopathology / Q000652:urine*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests
D015415:Biomarkers; D002614:Chelating Agents; D004492:Edetic Acid; D003404:Creatinine