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Kidney Week

Abstract: FR-PO271

Changes in FGF23 and Soluble Klotho Levels after Initiation of Hemodialysis

Session Information

Category: Mineral Disease

  • 1202 Mineral Disease: Vitamin D, PTH, FGF-23

Authors

  • Kawabata, Chiaki, Tokai University School of Medicine, Isehara, Japan
  • Komaba, Hirotaka, Tokai University School of Medicine, Isehara, Japan
  • Nakagawa, Yosuke, Tokai University School of Medicine, Isehara, Japan
  • Hamano, Naoto, Tokai University School of Medicine, Isehara, Japan
  • Koizumi, Masahiro, Tokai University School of Medicine, Isehara, Japan
  • Kanai, Genta, Tokai University School of Medicine, Isehara, Japan
  • Wada, Takehiko, Tokai University School of Medicine, Isehara, Japan
  • Fukagawa, Masafumi, Tokai University School of Medicine, Isehara, Japan
Background

FGF23 is markedly elevated in end stage of renal disease and these levels have been associated with increased risk of mortality. It has been suggested but not proved that long-term management of hyperphosphatemia is required to achieve sufficient reductions in FGF23 levels. Initiation of hemodialysis leads to a marked removal of phosphate from the body and resultant reductions in PTH levels, but the effect of hemodialysis initiation on FGF23 levels has not been explored.

Methods

We conducted a prospective observational study of twenty patients initiating hemodialysis. We follow upped over five days with four hemodialysis sessions. We did not change the prescription of vitamin D receptor activators, phosphate binders, or cinacalcet during the study period. We measured biochemical parameters of mineral metabolism including FGF23 pre and post each hemodialysis session, a total of 8 times. Serum full-length FGF23 levels were measured using a chemiluminescent enzyme immunoassay (Kyowa Medex, Co., Ltd) and soluble Klotho levels were measured using an enzyme linked immunosorbent assay (Immuno-Biological Laboratories, Co., Ltd).

Results

At baseline, serum levels were as follows; phosphorus, 5.6 ± 1.9 mg/dl; intact PTH, 299 (182-356) pg/ml; FGF23, 517 (300-919) pg/ml; and soluble Klotho, 297 ± 107 pg/ml. Initiation of hemodialysis led to a progressive reduction in serum phosphorus, intact PTH, and FGF23 levels (median percent changes from baseline to the start of the 4th hemodialysis session were -32%, -8%, and -43%, respectively). Prescription of vitamin D receptor activators did not modify the effect of hemodialysis initiation on FGF23 levels. There was no meaningful change in soluble Klotho levels.

Conclusion

FGF23 levels decrease drastically after initiation of hemodialysis. A marked removal of phosphorus by hemodialysis initiation could suppress the production of FGF23 by osteocytes. Our findings suggest a critical role of phosphorus retention in markedly elevated FGF23 and support the importance of serum phosphorus management for suppressing FGF23 production, which may have diverse toxic effects.