Cardiovascular, Renal, and Skeletal Complications in Patients With Post-Surgical Hypoparathyroidism

Inclusion Criteria: Patients only: * Chronic post surgical hypoparathyroidism diagnosed \> 5 years ago. (In case recruitment is too challenging, we will accept duration of disease of minimum one year. Including patients with longest duration of disease first.) * Require treatment with active vitamin D ≥ 1 µg/day Controls only: * No history of neck surgery * No history of parathyroid disease All participants: * Age ≥ 18 years * 25(OH)D vitamin ≥ 50 nmol/L * Serum magnesium ≥ 0,50 mmol/L * Able to read and understand Danish * Willing and able to sign the informed consent form Exclusion Criteria: * Estimated glomerular filtration rate (eGFR) \< 30 ml/min/1.73 m3 * Active cancer or former (except thyroid and basal cell skin) cancer treatment \< 5 year ago * Pregnancy, or breastfeeding \< 1 year ago * Untreated thyroid or liver diseases during the last year * Treatment with lithium within the last 4 weeks * Known allergy or sensitivity to iodine * Any reason that in the opinion of the investigator, that would prevent the patient from completing the study.