A comparison between three commercial kits for chromogranin A measurements.

Chromogranin (CgA) has been shown to be an excellent marker for neuroendocrine tumours. There are now three commercial assays on the market. We wanted to compare the usefulness of the different kits in a clinical situation. We have thus measured CgA in 77 patients and compared the results from the different methods. CgA was measured with three different commercial kits according to the recommendations from the manufacturers (CGA-RIA CT; CIS bio international, Gif-sur-Yvette cedex, France, DAKO Chromogranin A ELISA kit; DAKO A/S, Glostrup, Denmark and CgA; EuroDiagnostica, Malmö, Sweden). The sensitivity and specificity differed between the different kits. The CIS kit showed a sensitivity of 67% and a specificity of 96%. The sensitivity and specificity were both 85% for the DAKO kit and 93% and 88% respectively for the EuroDiagnostica assay. We have concluded that CgA is an important tumour marker for all neuroendocrine tumours. However, different analytical properties of the respective kits give different performances, a fact that must be taken into consideration when comparing results from different clinical studies. A recognised international standard for CgA would be a step on the way to harmonisation, but antibody selection and construction of the assays will probably still influence the results.