Journal of Bone Metabolism  2014;21(3):217-222

doi:10.11005/jbm.2014.21.3.217

Increase in the Serum Parathyroid Hormone Level During a Bisphosphonate Drug Holiday.

Yoon Kyung SONG 1 ; Jeong Min KIM ; Sun Jin PARK ; Seong Kyu LEE

Affiliations

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Keywords

Bisphosphonate; Calcium; Parathyroid hormone; Vitamin D

Country

Republic of Korea

Language

English

Abstract

After discontinuation of bisphosphonate therapy, an antiresorptive effect and antifracture protection persist for an undefined period. Patients are encouraged to continue calcium and vitamin D supplementation, during a bisphosphonate drug holiday. However, assessment of adequate calcium intake during the bisphosphonate drug holiday is difficult. Therefore, we measured the serum intact parathyroid hormone (PTH) level as a surrogate marker. A premenopausal woman discontinued bisphosphonate therapy, after 7.5 years of treatment. Two months later, blood calcium and phosphorus levels were normal, serum 25-hydroxyvitamin D level was 31.3 ng/mL, but serum PTH level had increased to 94.9 pg/mL. The elemental calcium supplement dose was increased to 600 mg/day, with no change in the cholecalciferol dose (400 IU). Her serum PTH levels decreased to 49.1 after 4 months and 32.9 pg/mL after 5 months. The serum PTH level may be helpful in assessing adequate calcium intake during a bisphosphonate drug holiday.