Assessment of the performance of a capture immunoassay for the bone isoform of alkaline phosphatase in serum.
We report the analytical validation of an immunocapture assay for the bone isoform of alkaline phosphatase in serum. A between batch imprecision of less than 10% was found, being about 8% at the upper limit of the reference range, and with a detection limit of 0.8 IU/l at 37 degrees C. The crossreactivity of the method with the liver isoform was found to be in the range of 3-13% depending on the method employed. Unexpectedly the correlation of results with a non-immunological method for the quantitation of bone ALP showed significant differences between samples from children and patients with Paget's disease, with an apparent lower level of capture in the case of children. These data suggest that there may be differences in the epitope recognised by the antibody, which may be due to the presence of different forms of bone enzyme in these two populations. The significance of these observations is not clear at this stage.
Milligan
T P
TP
Department of Clinical Biochemistry, St. Bartholomew's, London, UK.
Park
H R
HR
Noonan
K
K
Price
C P
CP
D000469:Alkaline Phosphatase / Q000097:blood* / Q000276:immunology; D001774:Blood Chemical Analysis / Q000379:methods / Q000706:statistics & numerical data; D001842:Bone and Bones / Q000201:enzymology*; D002648:Child; D003429:Cross Reactions; D005069:Evaluation Studies as Topic; D006801:Humans; D007118:Immunoassay / Q000379:methods* / Q000706:statistics & numerical data; D007527:Isoenzymes / Q000097:blood* / Q000276:immunology; D008099:Liver / Q000201:enzymology; D010001:Osteitis Deformans / Q000201:enzymology
D007527:Isoenzymes; D000469:Alkaline Phosphatase