DENVER—Fibroblast growth factor 23 (FGF-23) is positively associated with cinacalcet use, calcium, and phosphorus in hemodialysis (HD) patients, according to a study.

The study, by Magdalene M. Assimonand, PharmD, of Albany College of Pharmacy & Health Sciences in Albany, N.Y., also found that patients taking cinacalcet had worse secondary hyperparathyroidism (SHPT) and required larger doses of calcitriol despite a 6.9 month mean duration of cinacalcet therapy. Researchers concluded that cinacalcet use may be a surrogate marker for refractory SHPT.

FGF-23 regulates phosphate excretion and vitamin D metabolism, and directly reduces parathyroid hormone (PTH) secretion. PTH levels may remain elevated in dialysis patients despite elevated FGF-23 levels and use of therapy to control SHPT, the researchers explained. Limited data exist regarding the association between cinacalcet and FGF-23 in persistent SHPT.

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The study included 118 HD patients, of whom 57.6% were male. They had a mean age of 63.5 years and a mean dialysis vintage of 3.3 years. Log FGF-23 levels correlated positively with calcium, phosphorus, PTH, and HD vintage, and correlated negatively with age. Log FGF-23 levels were higher in cinacalcet users compared with nonusers. Patients taking cinacalcet had higher median PTH levels compared with nonusers (431.7 vs. 301.7 pg/mL) and received greater doses of intravenous calcitriol (3.6 vs. 2.0 mcg/week).