Challenges in the therapy of secondary hyperparathyroidism.

Derangements in mineral metabolism are known to occur early in the course of chronic kidney disease (CKD). Recent clinical practice guidelines are designed to focus on the problem early in the course of kidney disease, when it is recommended to evaluate the levels of parathyroid hormone (PTH) and to try to intervene early if the levels are elevated. To begin early intervention for hyperparathyroidism in chronic kidney disease will require involvement of primary care physicians and other subspecialty groups to identify the patients at risk and begin to intervene with measures to control hyperparathyroidism and its consequences on mineral metabolism. It has recently been demonstrated that chronic kidney disease is a significant risk factor for vitamin D deficiency and since abnormalities in vitamin D metabolism are important in the generation of hyperparathyroidism, this is an issue that needs direct attention. Studies are needed to assess the effects of correcting this vitamin D deficiency in early CKD. As kidney disease progresses, efforts to control hyperparathyroidism will likely need to be intensified and several therapeutic options are available, such as phosphate binders, repletion of vitamin D, the use of active vitamin D sterols, or the use of vitamin D analogs. In addition, it is important to define the appropriate PTH values that need to be achieved to minimize complications on bone. Such studies are in progress at the present time to validate the current more specific PTH assays. Strict guidelines have been proposed for the management of bone and mineral metabolism in patients with CKD stage V on dialysis, and although these challenging recommendations were initially opinion-based, there is mounting evidence which provides confirmation of these targets as relevant. Treatment options for patients on dialysis involve the full spectrum of agents which include phosphate binders, active vitamin D sterols (often given parenterally), the use of calcimimetic agents, surgical parathyroidectomy, and evaluation of appropriate levels of dialysate calcium. Similar to early stages of CKD, studies are in progress to refine the PTH targets with the newer PTH assays. With increased focus on the complications of bone and mineral metabolism as part of the continuum of chronic kidney disease, and with a variety of new therapies available, it is anticipated that improved patient outcomes should be achievable in this patient group.