Early control of PTH and FGF23 in normophosphatemic CKD patients: a new target in CKD-MBD therapy?

Abstract

Background and objectives: Levels of parathyroid hormone (PTH) and the phosphaturic hormone FGF23, a fibroblast growth factor (FGF) family member, increase early in chronic kidney disease (CKD) before the occurrence of hyperphosphatemia. This short-term 6-wk dose titration study evaluated the effect of two phosphate binders on PTH and FGF23 levels in patients with CKD stages 3 to 4.

Design, setting, participants, and measurements: Patients were randomized to receive over a 6-wk period either calcium acetate (n = 19) or sevelamer hydrochloride (n = 21).

Results: At baseline, patients presented with elevated fractional excretion of phosphate, serum PTH, and FGF23. During treatment with both phosphate binders there was a progressive decline in serum PTH and urinary phosphate, but no change in serum calcium or serum phosphate. Significant changes were observed for FGF23 only in sevelamer-treated patients.

Conclusions: This study confirms the positive effects of early prescription of phosphate binders on PTH control. Prospective and long-term studies are necessary to confirm the effects of sevelamer on serum FGF23 and the benefits of this decrease on outcomes.

Figures

Figure 1.

Absolutes changes in the levels of serum calcium (Ca), serum phosphate (P), urinary phosphate (uP), fractional excretion of phosphate (FeP), serum PTH, and serum FGF23 in patients treated with sevelamer hydrochloride (○) or calcium acetate (■) over a 6-wk period followed by a 2-wk washout period. Statistical comparisons within and between treatment groups are shown. Data are expressed as mean ± SD, except for FGF23 and PTH, which are expressed as median (25th to 75th percentile interval).

Figure 2.

Percentage change in serum FGF23 and PTH levels in patients treated with sevelamer hydrochloride (□) or calcium acetate (■) over a 6-wk period. Statistical comparisons within and between treatment groups are shown. Data are expressed as mean ± SD.