Relationship Between Aldosterone and Parathyroid Hormone, and the Effect of Angiotensin and Aldosterone Inhibition on Bone Health

Emerging evidence suggests a stimulating effect of parathyroid hormone (PTH) on the renin–angiotensin–aldosterone system (RAAS). In primary hyperparathyroidism, chronic-elevated PTH levels seem to stimulate the RAAS which may explain the increased risk of cardiovascular disease (CVD). In addition to increased PTH levels, low vitamin D levels may also directly increase risk of CVD, as vitamin D, itself, has been shown to inhibit the RAAS. Angiotensin II, aldosterone and cortisol all negatively impact bone health. Hyperaldosteronism is associated with a reversible secondary hyperparathyroidism due to increased renal calcium excretion. Moreover, the angiotensin II receptor is expressed by human parathyroid tissue, and angiotensin may therefore directly stimulates PTH secretion. An increased bone loss is found in patients with hyperaldosteronism. The angiotensin II receptor seems main responsible for the RAAS-initiated bone loss due to a receptor activator of NF-κB ligand-mediated activation of the osteoclasts. Available data suggest a reduced fracture rate and increased bone mineral density in patients treated with angiotensin II receptor blockers, whereas treatment with angiotensin-converting enzyme inhibitors causes the opposite effects. Mineralocorticoid receptor antagonists seem to be beneficial to bone in patients with hyperaldosteronism, but it is unknown whether this also applies to other individuals. Further long-term studies are needed to clarify the effect of RAAS inhibitors on bone health. RAAS inhibitors, are widely prescribed worldwide and beneficial as well as harmful effects may have large impact on bone health in the general population.