Secondary hyperparathyroidism in chronic renal failure: pathogenic and clinical aspects.

Secondary hyperparathyroidism occurs early in the course of chronic renal failure. Early in the course, a deficit of calcitriol and an abnormality in the calcium sensor receptor may be the important factors; later, with advanced renal failure, hyperphosphatemia becomes an additional important pathogenic factor. Important clinical problems in dialysis patients are as follows: (1) hyperphosphatemia, which contributes to high morbidity and mortality of dialysis patients (a clinical approach to maintaining a normal serum phosphorus is essential and is discussed in this review); (2) a high calcium X phosphorus product leading to coronary artery calcifications (factors leading to calcifications are also discussed); and (3) calciphylaxis, which has been observed with increasing frequency in these patients (an increase in the total calcium load may be the most important pathogenic factor leading to this syndrome). Therapeutic considerations regarding the use of new vitamin D analogues devoid of a hypercalcemic and/or a hyperphosphatemic effect are also mentioned.