Cardiovascular Disorders in Hemodialysis Calcium, Phosphorus and Vitamin D Disorders in Uremia Slatopolsky E, Brown A, Dusso A Ronco C, Brendolan A, Levin NW (eds): Cardiovascular Disorders in Hemodialysis. Contrib Nephrol. Basel, Karger, 2005, vol 149, pp 261-271 (DOI: 10.1159/000085687)
Abstract: Background: Alterations in calcium, phosphate (P) and vitamin D metabolism play a critical role in the development of secondary hyperparathyroidism (SH), parathyroid hyperplasia and soft tissue and vascular calcification. Methodology: Studies were performed in uremic dogs and rats fed a low and high P diet over a period of 1-4 months. In addition, in vitro studies were performed in normal parathyroid glands incubated in culture media containing 0.2mM P (low) or 2.0mM P (high). Results: Uremic rats maintained on a low P diet did not develop SH or parathyroid hyperplasia. There was an enhancement of p21, the suppressor of the cell cycle, in these parathyroid glands. Opposite results were obtained using a high P diet. There was an enhancement of transforming growth factor- and epidermal growth factor receptor, known enhancers of cell proliferation. In vitro studies demonstrated the direct effect of P on parathyroid hormone secretion. Conclusions: Early dietary P restriction prevents the development of SH and parathyroid hyperplasia. If dietary P restriction is applied to rats with established SH, there is a significant amelioration of SH and parathyroid hyperplasia. In addition, control of serum P in uremic patients is crucial in the prevention of vascular calcification. |
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