Current and Future Therapies for the Medical Management of Secondary Hyperparathyroidism

An Update on Phosphate Binders: A Dietitian's Perspective

Control of serum phosphorus (PO4) has been long recognized as a goal in the nutritional and medical management of the patients with chronic kidney disease. Phosphate-binding compounds were introduced in the 1970s for the treatment of hyperphosphatemia in patients on dialysis after it was observed that oral administration of aluminum hydroxide as an antacid also reduced serum PO4 levels. Forty years later, aluminum is very seldom used as a phosphate binder as many other safer compounds are now available. This article is a comprehensive review, geared to the renal dietitian, of the most common binder categories. It will discuss pharmacokinetics, side effects, initial and optimal doses, phosphate affinity, and controversies of use. It will also review two novel approaches to serum PO4 management in chronic kidney disease patients receiving dialysis and provide a new calculation by which binders can be compared.

New Therapies for Uremic Secondary Hyperparathyroidism

Secondary hyperparathyroidism (SHPT) is a common and serious complication of chronic kidney disease (CKD). It affects more than 300,000 end-stage renal disease patients treated by dialysis and probably more than 3 million patients with CKD worldwide. For a long time, traditional therapies for SHPT had consisted of correcting the hypocalcemia using calcium salts and vitamin D derivatives, preventing the hyperphosphatemia by calcium- or aluminum-containing intestinal phosphate binders, and recently by using no metal-containing intestinal phosphate binders; however, these therapies are limited by the occurrence of hypercalcemia, hyperphosphatemia, and the lack of specificity and long-term efficacy. Moreover, surgical parathyroidectomy (PTX), which remains the gold standard therapy, is not exempt from risk. PTX exposes patients to anesthesia risks, presurgical and postsurgical complications, and in many cases a permanent state of hypoparathyroidism. Thus, the medical treatment of SHPT became an ideal target for the development of new therapies and strategies. The purpose of this article is to provide an overview of these new therapies, including vitamin D analogs, intestinal phosphate binders, calcimimetics, parathyroidectomies, tyrosine kinase inhibitors, azydothymidine, anticalcineurins, N-terminal truncated parathyroid hormone fragments, bisphosphonates, calcitonin, osteoprotegerin, and others. The use of these new therapies alone or in combination may help to optimize the future treatment of SHPT in CKD patients.

Vitamin D therapy in patients with chronic renal disease: the role of the renal dietitian

Chronic renal failure causes decreased vitamin D production, which profoundly alters parathyroid hormone (PTH) metabolism, and calcium and phosphorus balance. Correcting this deficiency is an important strategy in managing secondary hyperparathyroidism (SHPT) and helping to restore mineral balance. However, hypercalcemia and hyperphosphatemia are common side effects that hamper vitamin D hormone therapy by increasing dietary calcium and phosphorus absorption. This limitation has led to the development of D-hormone analogs that retain the ability to suppress PTH levels without causing drastic changes in calcium and phosphorus metabolism. These analogs have the potential to advance the management of SHPT. Renal dietitians can play a leading role in ensuring successful management of SHPT by participating in early patient intervention for abnormal mineral and vitamin D metabolism, by encouraging long-term phosphorus control, and by updating and implementing clinical protocols that promote optimal hormone levels (D and PTH), mineral levels (phosphorus and calcium), and nutritional factors.