Physiologic Interactions Between the Adrenal- and the Parathyroid Glands (AldOst)

To investigate possible physiologic interactions between the adrenal- and the parathyroid glands in patients with secondary hyperparathyroidism.

In primary hyperparathyroidism, chronic-elevated PTH levels seem to stimulate the renin-angiotensin-aldosterone system (RAAS) which may explain the increased risk of cardiovascular disease. In addition to increased PTH levels, vitamin D has been shown to inhibit the RAAS. However, a possible physiologic interaction needs further investigation. The purpose of the study is to investigate changes in the RAAS in otherwise healthy postmenopausal women with secondary hyperparathyroidism due to vitamin D deficiency when p-PTH is normalized. Furthermore, we will evaluate whether an angiotensin 2 receptor blocker can lower PTH in patients with secondary hyperparathyroidism.

2 weeks of Placebo Valsartan, one tablet per day. Placebo tablets are identical in regards to size and appearance to the experimental intervention tablet.

12 weeks of daily Placebo cholecalciferol treatment. Placebo tablets are identical in regards to size and appearance to the experimental intervention tablet.

Effects on muscle strength (isometric tests of flexion and extension of thigh and hand), two function-tests (timed up-and go and timed stand-and-sit),

Bone quality in spine and hip as assessed by high resolution quantitative computed tomography HRQCT-scans

Bone quality in ankle and forearm as assessed by high resolution peripheral quantitative computed tomography HRpQCT-scans

Effects of intervention on biochemical markers of calcium and bone metabolism, such as calcium, phosphate, parathyroid hormone, calcitriol, vitamin D-binding protein, bone-specific alkaline phosphatase, osteocalcin, and N-terminal propeptide of type 1 procollagen (P1NP). Also C-terminal telopeptide of type 1 collagen (CTX) and N-telopeptide of type 1 collagen (NTX) among others.

Inclusion Criteria: Secondary hyperparathyroidism due to Vitamin D deficiency Exclusion Criteria: Cardiovascular disease Renal failure Liver failure Treatment with antihypertensive medication or diuretics Treatment with lithium, NSAID or glucocorticoids Calcium supplement more than 500 mg per day or Vitamin D supplement more than 25 microgram per day Medical treatment for osteoporosis Systolic blood pressure below 120 mmHg Hypercalcaemia (more than 1,33mmol/L) Use of solarium or planned trip to countries, that might increase the endogenous vitamin D synthesis Allergic reaction to ACEi or ARBs.

Bislev LS, Wamberg L, Rolighed L, Grove-Laugesen D, Rejnmark L. Effect of Daily Vitamin D3 Supplementation on Muscle Health: An Individual Participant Meta-analysis. J Clin Endocrinol Metab. 2022 Apr 19;107(5):1317-1327. doi: 10.1210/clinem/dgac004.

Bislev LS, Langagergaard Rodbro L, Rolighed L, Sikjaer T, Rejnmark L. Bone Microstructure in Response to Vitamin D3 Supplementation: A Randomized Placebo-Controlled Trial. Calcif Tissue Int. 2019 Feb;104(2):160-170. doi: 10.1007/s00223-018-0481-6. Epub 2018 Oct 6.

Bislev LS, Langagergaard Rodbro L, Rolighed L, Sikjaer T, Rejnmark L. Effects of Vitamin D3 Supplementation on Muscle Strength, Mass, and Physical Performance in Women with Vitamin D Insufficiency: A Randomized Placebo-Controlled Trial. Calcif Tissue Int. 2018 Nov;103(5):483-493. doi: 10.1007/s00223-018-0443-z. Epub 2018 Jun 21.