[Importance of the "adequate blood phosphorus" concept as a risk factor for hyperphosphatemia]

Hyperphosphatemia is an important risk factor of secondary hyperparathyroidism and extraosseous calcifications in chronic renal failure patients. In this study our hypothesis is that physicians misconception of adequate phosphatemia is a risk factor for hyperphosphatemia. In 1999 GEMOR sent a renal osteodystrophy inquiry to different hemodialysis centers in Argentina. It included 80 dialysis centers in 17 Argentinian provinces. The enquire had 33 questions about renal osteodystrophy. Here we report the section related to phosphorous metabolism. We obtained responses from 80 dialysis centers (4,512 dialysis patients), which represents about 24% of Argentinian dialysis centers. Physicians considered phosphorous levels between 4.5 to 5.5 mg/dl in 83.5% of centers as adequate, and between 5.5 to 6.5 mg/dl in 10.1%. Five out of 77 centers reported that they had no patients with hyperphosphatemia. The percentage of hemodialysis patients that had more than 6 mg/dl in each center was 28.8 +/- 15.9%. Those centers that aimed for phosphatemia between 5.5 and 6.5 mg/dl, had a higher percentage of patients with phosphatemia above 6 mg/dl than those aiming for between 4.5 and 5.5 mg/dl (42.8 +/- 16.7 vs 27.1 +/- 15.2% respectively, p = 0.007), and had higher mean of phosphatemia (6.4 +/- 0.7 vs 5.3 +/- 0.7 mg/dl respectively, p = 0.0001), than the last group. In conclusion, a higher mean phosphate level was obtained in hemodialysis centers where physicians considered higher pre-dialysis target levels. Some centers had no patients with hyperphosphatemia (neglect or good control?).