['The calcimimetic cinacalcet lowers parathyroid hormone (PTH), calcium (Ca) and phosphorus (P) in dialysis patients with secondary hyperparathyroidism (SHPT). We explored serum P changes in dialysis patients treated with cinacalcet, while controlling for vitamin D sterol and phosphate binder (PB) changes, based on data from the pan-European observational study ECHO.', 'Patients were categorized by serum P change (decreased/unchanged/increased) at 12 months after starting cinacalcet and subcategorized by vitamin D sterol and PB dose changes (decreased/unchanged/increased). The impact of PTH, Ca and P, and vitamin D sterol, PB and cinacalcet doses (absolute values and/or change) was evaluated. Predictors of P change were explored using univariate and multivariate general linear models (GLM) and logistic regression analysis.', 'At Month 12, 661 (41%) of 1607 patients had decreased, 61 (4%) unchanged and 400 (25%) increased serum P, while 485 patients had missing data. In 45% of the patients with serum P reduction, vitamin D was either increased or unchanged and P binders decreased or unchanged. PTH was a key predictor of serum P reduction, with an estimated 3% decrease in P per 10% reduction in PTH. Changes in vitamin D sterol and PB doses were not generally significant factors in GLM and regression analyses.'] Does serum phosphorus reduction in dialysis patients treated with cinacalcet for secondary hyperparathyroidism result mainly from parathyroid hormone reduction?