Skip to main content
Fig. 2 | Clinical Diabetes and Endocrinology

Fig. 2

From: Interpretation of common endocrine laboratory tests: technical pitfalls, their mechanisms and practical considerations

Fig. 2

Illustration of non-competitive “sandwich” immunoassay. a In non-competitive “sandwich” immunoassay, capture antibodies are anchored to a solid phase in the testing tube. Then, the sample containing the studied hormone as well as the signal antibodies are added. b The hormone binds to the capture antibody from one end and to the signal antibody from the other end, forming antibody-hormone-antibody “sandwich”. The unbound signal antibodies is then washed out and the signal from the remaining “sandwiches” is measured. The higher the concentration of the hormone (illustrated in green), the more “sandwiches” will be formed, and thus, the higher signal will be measured. In other words, the stronger the signal, the more of the endogenous hormone is present in the sample and vice versa (i.e. the signal is directly proportional to the hormone concentration)

Back to article page