The aim of this study is to investigate the effect of daily treatment with Indapamide for 14 days on urinary calcium excretion in patients with post surgical hypoparathyroidisme.

The aim of this study is to investigate the effect of daily treatment with Indapamide for 14 days on urinary calcium excretion in patients with post surgical hypoparathyroidisme.

Patients will do weekly blood sampling and 24 hour urine collection every second week.

Inclusion Criteria:

1. Chronic post surgical hypoparathyroidism diagnosed > 1 year ago
2. Age ≥ 18 years
3. Require treatment with active vitamin D ≥ 1 µg/day
4. Ionized plasma calcium between 1.15-1.25 mmol/L
5. 25(OH)D vitamin ≥ 50 nmol/L
6. Plasma magnesium > 0.65 mmol/L
7. Able to read and understand Danish
8. Willing and able to sign the informed consent form

Exclusion Criteria:

1. Estimated glomerular filtration rate (eGFR) < 30 ml/min/1.73 m3

2. Active cancer or former (except thyroid and basal cell skin) cancer treatment < 1 year ago

3. Pregnancy, pregnancy plans, or breastfeeding < 1 year ago

4. Abnormal arterial pressure at time of screening defined as symptomatic hypotension or systolic blood pressure < 100 mmHg

5. Plasma potassium < 3.5 mmol/L

6. Any current disease that might affect the calcium metabolism such as but not limited to:

   1. Recent prolonged immobility
   2. Untreated diabetes (HbA1c > 53 mmol/mol)
   3. Severe liver disease or hepatic encephalopathy
   4. Untreated thyroid disease

7. Current disease that might affect gastrointestinal absorption

8. Use of medications such as lithium or diuretics within 4 weeks prior to start of treatment

9. Known allergy or sensitivity to Indapamide, its excipients or sulfonamides

10. Known galactosemia, lactase deficiency, or glucose-galactose malabsorption

Only IPD used in the results publication

start data is time of publication and end 5 years after publication

By contacting the leading author of the publication in order to make a data sharing agreement, which should be signed. Proposal for agreement must contain planned analyses. Statistical analyses have to be approved by independent review before published. Data sharing agreement needs to be approved by the Technology Transfer Office (TTO), Aarhus University Hospital, Denmark