The laboratories comprising the SAS hormone group represent a network of specialist endocrine services across England and Wales. Each laboratory is headed by an expert in the field of laboratory endocrinology and provides at least one fully characterized specialist endocrine assay. The hormone group collectively provides 40 endocrine assays covering all the endocrine organs. This ensures that a full spectrum of clinically essential assays is provided across the network. Moreover, we aim to ensure that each analyte is provided by more that one laboratories to ensure provision of a backup service.