Vitamin D Research Today is a free monthly online journal that collates and summarizes the latest research about Vitamin D, including details on sources, melanin, benefits, deficiency, supplements, calcium absorption.

Calcium, phosphorus and vitamin D disorders in uremia.

Slatopolsky E, Brown A, Dusso A

Washington University School of Medicine, Department of Medicine, Renal Division, St. Louis, MO 63110, USA. eslatopo@im.wustl.edu

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 0.2 mM P (low) or 2.0 mM 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-alpha 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.

Published 6 May 2005 in Contrib Nephrol, 149: 261-71.
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