The aim of this study is to evaluate, for patients with post-thyroidectomy hypoparathyroidism (HoPT), the severity of their HoPT and to validate clinical scores from a self-administered questionnaire related to this disease (questionnaire which evaluates the severity of clinical symptoms related to HoPT and their impact on quality of life) in order to assess the severity of HoPT and to optimize support.

Total thyroidectomy is a procedure very frequently performed in France (and worldwide. Around 35,000 patients are operated on each year in France. Among its complications, hypoparathyroidism (HoPT) results from a suppression or a significant decrease of parathyroid hormone (PTH) secretion leading to hypocalcemia associated with urinary calcium leakage.

The frequency of definitive HoPT (at least 6 months postoperative) varies from 1 to 10% (Sitges-Serra et al. Br J Surg, 2010, Duclos BMJ 2012). It is often underestimated by operators (Cho et al. Endocr Pract, 2014). Our team has previously shown that this HoPT is responsible for a significant impairment in quality of life (mental and physical) and voice (Frey et al. Ann Surg, 2021).

Despite the existence of treatment guidelines, only 26 to 32% of patients in French series are treated according to international recommendations (Bertocchio et al. Endocr Connect, 2022). It is therefore important to be able to assess the severity of HoPT and to validate a clinical score using a self-administered questionnaire related to this disease (questionnaire which assesses the severity of the clinical symptoms linked to HoPT and their impact on the quality of life).

Only patients with post-thyroidectomy HoPT will be included in the present study. Patients who underwent total thyroidectomy in the department of Loire-Atlantique will be prospectively included if they display post-operative HoPT. In addition, HoPT patients previously operated on and followed up in Loire-Atlantique, as well as patients from the "Hypoparathyroidisme France" association (https://hypopara.fr) and HoPT patients who have been included in the ThyrQol and Fothyr studies (Mirallié et al. Eur J Endocrinol, 2020, Blanchard et al. BJS Open, 2017) will also be included.The data collected will be routine biological data (usual blood and urine tests), responses to the SF36 questionnaire (validated quality of life questionnaire) and responses to a questionnaire that will assess the frequency and impact on the daily life of the symptoms reported by these patients. This questionnaire contains items related with symptoms that are frequently displayed by these patients and that are responsible for an impaired quality of life, in accordance with the data of the literature, our previous study (Frey et al. Ann Surg, 2021) and a discussion with the members of the association Hypoparathyroidism France.

Inclusion Criteria:

• Major patient
• Patients undergoing total thyroidectomy
• Patients with permanent hypoparathyroidism defined by a parathyroid hormone concentration ≤ 25 pg/mL more than 6 months after surgery and who require vitamin and calcium therapy.
• Not being opposed to participating in the study (questionnaires will be sent with the study information note. If the patient returns the questionnaires: we will consider that he/she is not opposed to participate in this study)
• Participants must be affiliated to a social security system

Exclusion Criteria:

• Pregnant women when filling out questionnaires (the child's parathyroids can correct the mother's hypoparathyroidism)
• Minors or protected patients (under guardianship)
• Patients under court protection
• Patients on long-term vitamin-calcium therapy after total thyroidectomy whose PTH concentration has not been controlled or whose concentration is higher than 25 pg/mL.
• Hypoparathyroid patients of other origin than post-thyroidectomy

adult patients who have undergone total thyroidectomy and who have definitive hypoparathyroidism