[Peculiar problems of phosphocalcium metabolism in chronic renal insufficiency]

Chronic renal failure is associated with a disturbance of calcium and phosphate metabolism. During the initial stage of chronic renal failure plasma calcium and phosphorus are either slightly diminished or at the lower limit of the normal range, most probably due to a decrease in renal 1-alpha-hydroxylase activity. This leads to a decrease in circulating calcitriol and a stimulation of parathyroid hormone secretion. The underlying anomaly could be an as yet hypothetical elevation of the cytoplasmic phosphorus concentration within the renal tubular epithelium. During more advanced stages of chronic renal failure, a retention of phosphate occurs which induces hyperphosphatemia and contributes, either directly or indirectly, to the progressive worsening of secondary hyperparathyroidism with its skeletal expression of renal osteodystrophy.