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Development and evaluation of three immunofluorometric assays that measure different forms of osteocalcin in serum

Kakonen, S M; Hellman, J; Karp, M; Laaksonen, P; Obrant, Karl LU ; Vaananen, H K; Lovgren, T and Pettersson, K (2000) In Clinical Chemistry 46(3). p.332-337
Abstract
BACKGROUND: Circulating human osteocalcin (hOC) has been used as a marker of bone formation. Our aim was to validate three immunofluorometric assays (IFMAs), measuring different forms of hOC. METHODS: The two-site IFMAs were based on previously characterized monoclonal antibodies. Assay 2 recognized intact hOC, assays 4 and 9 measured the NH(2)-terminal mid-fragment and the intact hOC. In addition, assay 9 required hOC to be gamma-carboxylated. RESULTS: A 76-79% increase of serum immunoreactive hOC was found in the postmenopausal group compared with the premenopausal group with all IFMAs. With EDTA-plasma samples, the observed increases were lower (49-65%). The hOC concentration in the postmenopausal group receiving hormone replacement... (More)
BACKGROUND: Circulating human osteocalcin (hOC) has been used as a marker of bone formation. Our aim was to validate three immunofluorometric assays (IFMAs), measuring different forms of hOC. METHODS: The two-site IFMAs were based on previously characterized monoclonal antibodies. Assay 2 recognized intact hOC, assays 4 and 9 measured the NH(2)-terminal mid-fragment and the intact hOC. In addition, assay 9 required hOC to be gamma-carboxylated. RESULTS: A 76-79% increase of serum immunoreactive hOC was found in the postmenopausal group compared with the premenopausal group with all IFMAs. With EDTA-plasma samples, the observed increases were lower (49-65%). The hOC concentration in the postmenopausal group receiving hormone replacement therapy was 42-44% lower than that in the postmenopausal control group in both serum and EDTA-plasma samples. The depressed carboxylation in warfarin-treated patients was accompanied by lower results in assay 9. The ratio of assay 9 to assay 4 totally discriminated the warfarin-treated patients from the controls. Assay 9 showed the smallest decreases in measured hOC after storage of serum or plasma for 4 weeks at 4 degrees C, followed by assay 4 and assay 2. Results from the last assay were <17% of their initial values after 4 weeks of storage. No diurnal variation was observed with assay 9 as opposed to the two other IFMAs. CONCLUSION: The three assays with their distinct specificity profiles (intact vs fragmented and carboxylated vs decarboxylated hOC) may provide valuable tools for investigating the significance of different hOC forms in various bone-related diseases. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Clinical Chemistry
volume
46
issue
3
pages
332 - 337
publisher
American Association for Clinical Chemistry
external identifiers
  • pmid:10702519
  • scopus:0034106665
ISSN
0009-9147
language
English
LU publication?
yes
id
ebfd0a09-4c9a-4f0d-8bfe-bb861c34ce17 (old id 1117451)
alternative location
http://www.clinchem.org/cgi/content/abstract/46/3/332
date added to LUP
2008-06-27 12:27:34
date last changed
2017-01-01 05:04:49
@article{ebfd0a09-4c9a-4f0d-8bfe-bb861c34ce17,
  abstract     = {BACKGROUND: Circulating human osteocalcin (hOC) has been used as a marker of bone formation. Our aim was to validate three immunofluorometric assays (IFMAs), measuring different forms of hOC. METHODS: The two-site IFMAs were based on previously characterized monoclonal antibodies. Assay 2 recognized intact hOC, assays 4 and 9 measured the NH(2)-terminal mid-fragment and the intact hOC. In addition, assay 9 required hOC to be gamma-carboxylated. RESULTS: A 76-79% increase of serum immunoreactive hOC was found in the postmenopausal group compared with the premenopausal group with all IFMAs. With EDTA-plasma samples, the observed increases were lower (49-65%). The hOC concentration in the postmenopausal group receiving hormone replacement therapy was 42-44% lower than that in the postmenopausal control group in both serum and EDTA-plasma samples. The depressed carboxylation in warfarin-treated patients was accompanied by lower results in assay 9. The ratio of assay 9 to assay 4 totally discriminated the warfarin-treated patients from the controls. Assay 9 showed the smallest decreases in measured hOC after storage of serum or plasma for 4 weeks at 4 degrees C, followed by assay 4 and assay 2. Results from the last assay were &lt;17% of their initial values after 4 weeks of storage. No diurnal variation was observed with assay 9 as opposed to the two other IFMAs. CONCLUSION: The three assays with their distinct specificity profiles (intact vs fragmented and carboxylated vs decarboxylated hOC) may provide valuable tools for investigating the significance of different hOC forms in various bone-related diseases.},
  author       = {Kakonen, S M and Hellman, J and Karp, M and Laaksonen, P and Obrant, Karl and Vaananen, H K and Lovgren, T and Pettersson, K},
  issn         = {0009-9147},
  language     = {eng},
  number       = {3},
  pages        = {332--337},
  publisher    = {American Association for Clinical Chemistry},
  series       = {Clinical Chemistry},
  title        = {Development and evaluation of three immunofluorometric assays that measure different forms of osteocalcin in serum},
  volume       = {46},
  year         = {2000},
}