Date of this Version
United States Patent Number: 5,620,856
The invention provides method and kits for detecting a metallic cation in a sample of a body fluid. The preferred method and kits include the use of at least two different types of antibodies having different specificities. In the preferred method, the sample of body fluid can be contacted with an effective amount of a capture antibody specific for a naturally occurring polypeptide that can bind the metallic cation to form a first antigen-antibody complex. An effective amount of an antibody specific for an epitope on a metallic cation-naturally occurring polypeptide complex or an antibody specific for a metallic cation is added to the first antigen-antibody complex to form a second antigen-antibody complex. The amount of the metallic cation in the sample of body fluid is determined by detecting the amount of the second antigen-antibody complex.