Dialysis – Transplantation

Kidney International (2005) 67, 1120–1125; doi:10.1111/j.1523-1755.2005.00178.x

Pretreatment serum FGF-23 levels predict the efficacy of calcitriol therapy in dialysis patients

JUNICHIRO J KAZAMA, FUMINORI SATO, KENTARO OMORI, HITOMI HAMA, SUGURU YAMAMOTO, HIROKI MARUYAMA, ICHIEI NARITA, FUMITAKE GEJYO, TAKEYOSHI YAMASHITA, SEIJI FUKUMOTO and MASAFUMI FUKAGAWA

Division of Clinical Nephrology and Rheumatology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan; Pharmaceutical Research Labs, KIRIN Brewery Co., Ltd., Takasaki, Japan; Division of Laboratory Medicine, University of Tokyo Faculty of Medicine, Bunkyo, Japan; and Division of Nephrology and Dialysis Center, Kobe University School of Medicine, Kobe, Japan

Correspondence: Junichiro J. Kazama, M.D., Ph.D., FJSIM, Division of Clinical Nephrology and Rheumatology, Niigata University Graduate School of Medical and Dental Sciences, 1–751 Asahimachi-Dori, Niigata, Niigata 951–8510 Japan. E-mail:jjkaz@med.niigata-u.ac.jp

Received 26 July 2004; Revised 31 August 2004; Accepted 22 September 2004.

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Abstract

Pretreatment serum FGF-23 levels predict the efficacy of calcitriol therapy in dialysis patients.

Background

 

The predictor for the result of calcitriol therapy would be useful in the clinical practice of secondary hyperparathyroidism. Fibroblast growth factor-23 (FGF-23) is a newly found circulating phosphaturic factor. Its circulating level is elevated in uremia.

Methods

 

Dialysis patients with plasma intact parathyroid hormone (iPTH) levels greater than 300 pg/mL were included in the study. Calcitriol was intravenously injected three times a week. The patients whose plasma iPTH levels dropped below 300 pg/mL within 24 weeks were defined as those who had been successfully treated. A sandwich enzyme-linked immunosorbent assay (ELISA) system that detects human FGF-23 was applied.

Results

 

Sixty-two patients were analyzed. The pretreatment FGF-23 levels were related to the iPTH levels, calcium times phosphate product levels, and history of active vitamin D therapy. The pretreatment FGF-23, iPTH, and calcium levels were lower in the patients who would be successfully treated with calcitriol. A logistic regression study revealed that the pretreatment iPTH and FGF-23 levels significantly affected the therapy results. Analyses using a receiver-operated curve revealed that FGF-23 was the best screening test for identifying patients with future refractory response to calcitriol therapy. The treatment would be successful in 88.2% of those with FGF-23 less than or equal to9860 ng/L and iPTH less than or equal to591 pg/mL, while it would be successful in only 4.2% of those with FGF-23 >9860 ng/L and iPTH >591 pg/mL.

Conclusion

 

Pretreatment serum FGF-23 levels were a good indicator in predicting the response to calcitriol therapy. The measurement of serum FGF-23 levels, especially in combination with iPTH levels, is a promising laboratory examination for the clinical practice of secondary hyperparathyroidism.

Keywords:

fibroblast growth factor-23 (FGF-23), intact parathyroid hormone (iPTH), calcitriol, secondary hyperparathyroidism

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