Product: 2 MET (Metanephrine + Normetanephrine) Plasma RIA
2 MET (Metanephrine + Normetanephrine) Plasma RIA
: 2 x 100 determinations
: 500 µl
: MT 36-3600 pg/ml; NMT 48-4800 pg/ml
: 15 min, 1 h, 2 h, 15 min
: I-125 < 100 kBq
: MT: 19 pg/ml; NMT: 23 pg/ml
Intended use and principle of the test
125 I – Radioimmunoassay for the quantitative determination of free Metanephrine and free Normetanephrine in plasma.
First, the plasma proteins are removed by precipitation. Then the metanephrine (metadrenaline) and normetanephrine (normetadrenaline) are quantitatively acylated.
The assay procedure follows the basic principle of radioimmunoassay, involving competition between a radioactive and a non-radioactive antigen for a fixed number of antibody binding sites. The amount of 125I-labelled antigen bound to the antibody is inversely proportional to the analyte concentration of the sample. When the system is in equilibrium, the antibody bound radioactivity is precipitated with a second antibody in the presence of polyethylene glycol. The precipitate is counted in a gamma counter. Quantification of unknown samples is achieved by comparing their activity with a reference curve prepared with known standards.
The antisera used in this test kit only recognise the biologically relevant L-forms of metanephrines.
Commercially available synthetic normetanephrine or metanephrine is always a mixture of the Dand L-forms. The ratio between both forms differs widely from lot to lot. This has important implications if synthetic metanephrines are used to enrich native samples. As only about 50% of the synthetic metanephrines, i.e. the L-portion, will be detected by use of this kit, these samples will be underestimated. Therefore only native samples should be used.