The EuRRECa Core Registry is designed to collect core information on a wide range of rare endocrine and bone conditions listed in the Conditions Dictionary below. The fields that are used to collect this core information include the core data elements that are recommended by European standards for data collection and a high proportion of them have universal identifiers. In addition, the Core Registry collects clinician and patient reported generic outcomes. Condition-specific outcomes can also be collected and have been developed for some conditions and can be developed for others. Please contact the EuRRECa team if you are interested in developing condition-specific outcomes for any condition that is not covered at the moment.