This main aim of this study is to check the level of knowledge and assess attitudes and behaviors of both participants and prescribing physicians regarding the risks and safe use of NATPARA. The survey will be done via internet, telephone, or paper and participants will be able to choose the method that is preferred. No study medicines will be provided to patients in this study.

Participant inclusion criteria:

• Participants who are 18 years of age or older and who have been approved for NATPARA and a part of the SUP Program prior to survey implementation are eligible to participate in the survey.

• A caregiver may participate in this survey on behalf of a participant who is a part of the SUP Program and who is eligible but unable to complete the survey.

Prescribing physician inclusion criteria:

• HCPs in the United States (US) who can provide a 10-digit NPI number and who are certified in the NATPARA REMS by successfully completing the NATPARA REMS Program Training Module for Prescribing Physicians, including the Knowledge Assessment, and submitting a NATPARA REMS Program Prescribing Physician Enrollment Form are eligible for participation in the survey and a part of the SUP Program.

Participant and Prescribing Physician exclusion criteria:

• Respondents who do not agree to participate in the survey will be excluded.
• Survey respondents who have been employed or whose immediate family members have been employed by NPS, Shire, Takeda, United BioSource LLC, (UBC), or the Food and Drug Administration (FDA) are not eligible to participate in the survey and will be excluded.
• Respondents who reported having a conflict of interest will be excluded.
• Respondents who are not part of the SUP program will be excluded.

Participant exclusion criteria:

• Participants who do not agree to participate in the survey will be excluded.
• Participants who have opted out of receiving communications will be excluded.

Participants who have been approved for NATPARA and a part of the SUP program prior to survey implementation and prescribing physicians who can provide a 10-digit NPI number and who are certified in the NATPARA REMS by successfully completing the NATPARA REMS program training module for prescribing physicians, including the knowledge assessment, and submitting a NATPARA REMS program prescribing physician enrollment form are eligible for participation in the survey.

Takeda provides access to the de-identified individual participant data (IPD) for eligible studies to aid qualified researchers in addressing legitimate scientific objectives (Takeda's data sharing commitment is available on https://clinicaltrials.takeda.com/takedas-commitment?commitment=5). These IPDs will be provided in a secure research environment following approval of a data sharing request, and under the terms of a data sharing agreement.

IPD from eligible studies will be shared with qualified researchers according to the criteria and process described on https://vivli.org/ourmember/takeda/ For approved requests, the researchers will be provided access to anonymized data (to respect patient privacy in line with applicable laws and regulations) and with information necessary to address the research objectives under the terms of a data sharing agreement.