Conversion between bromcresol green- and bromcresol purple-measured albumin in renal disease.
BACKGROUND
Albumin measured by a bromcresol purple dye-binding assay (Alb(BCP)) agrees more closely with the gold standard of immunonephelometry than does bromcresol green (Alb(BCG)) measurement. Both tests are in current clinical use. A method for converting between the two would be useful.


METHODS
We measured albumin by bromcresol green and bromcresol purple in 535 patients, 155 of whom had renal disease. We randomly divided data from the patients with renal disease into two equal-sized sets, and used one set to derive, and the remaining set to validate, a regression equation relating the two values.


RESULTS
The relationship Alb(BCG)=5.5+Alb(BCP) performed very well in both the renal patient validation set and in the data from 380 unselected in-patients and out-patients. Intraclass correlations for agreement between measured Alb(BCG) and predicted Alb(BCG) was 0.98 in both analyses.


CONCLUSIONS
The ability to convert between these measurements will be of use in clinical situations where the absolute value of the serum albumin is important, when data from laboratories using different methodologies must be combined, and in the application of the Modification of Diet in Renal Disease formula to estimate glomerular filtration rate in patients whose albumin has been measured by bromcresol purple.
Clase
C M
CM
Division of Nephrology, Dalhousie University, Halifax, Nova Scotia, B3H 1V8, Canada.
St Pierre
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MW
Churchill
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DN
D001961:Bromcresol Green; D001962:Bromcresol Purple; D006801:Humans; D007202:Indicators and Reagents; D007674:Kidney Diseases / Q000097:blood*; D016018:Least-Squares Analysis; D011897:Random Allocation; D012044:Regression Analysis; D012709:Serum Albumin / Q000032:analysis*
D007202:Indicators and Reagents; D012709:Serum Albumin; D001962:Bromcresol Purple; D001961:Bromcresol Green