ESPE Abstracts (2014) 82 P-D-2-3-307

Suppression of Bone Turnover and its Determinants in Children Receiving Bisphosphonate Therapy

Andreas Kyriakoua, Jane D McNeillyb, Martin McMillana, Guftar M Shaikha, Avril Masona & Syed Faisal Ahmeda


aDevelopmental Endocrine Research Group, University of Glasgow, Glasgow, UK; bDepartment of Biochemistry, RHSC, Glasgow, UK


Background: Bisphosphonate therapy (BPT) reduces osteoclast activity and may be associated with adynamic bone turnover. The extent of suppression of bone turnover and its determinants are unclear.

Method: Markers of bone metabolism were evaluated in 15 children (9M/6F) undergoing BPT for osteoporosis. The median age at first biochemical assessment was 10.8 years (0.16, 16.3). Serum type I collagen cross-linked C-telopeptide (CTX), alkaline phosphatase (ALP), calcium(CA), phosphate(P), parathyroid hormone (PTH) and 25 hydroxy vitamin D (VitD) were measured on day 1 of each BPT cycle. The CTX was expressed as a centile of the reference range in healthy children.

Results: The median interval between the first BPT cycle and first biochemical assessment was 0.67 years (0.17, 4.8). The median duration of observation was 1.1 years (0.58, 3.3) and the median number of samples per patient was 5 (3, 9) (Table 1). The median CTX centile was 2.4 (0.5, 7.1), thus below 10th centile, throughout the duration of observation (P<0.0001). ALP was negatively correlated with the duration of treatment (r−0.35, P<0.05) and positively correlated with CTX(r=0.72, P<0.0001). Median CTX in patients who had (n=4) and did not have consistently low VitD was 26.1% (12.8, 51) and 19.6% (3.4, 35.7)(P<0.05). PTH was positively correlated with CTX (r=0.51, P<0.05).

Table 1.
Time since start BPT (years)
n Reference range 0.5 1 1.5 2 3 >3
7 10 8 8 5 5
CTXcentile 2.8 (0.7, 4.1) 2.8 (0.6, 4.9) 2.7 (0.5, 3.8) 2.8 (0.5, 5.5) 2.1 (1.4, 7.1) 2.1 (1.0, 4.9)
ALP(U/l) 60–424 351 (62, 500) 261 (49, 421) 192 (36, 455) 141 (39, 396) 215 (136, 346) 145 (105, 274)
PTH(pmol/l) 1.6–7.5 2.9 (1.4, 4.5) 2.35 (1.0, 6.9) 3.35 (2.8, 6.0) 3.4 (2.1, 7.8) 2.95 (2.5, 5.1) 4.3 (2.8, 5.6)
VitD(nmol/l) >40 47 (26, 78) 36 (19, 108) 15 (14, 44) 23 (14, 36) 31 (23, 38) 57 (34, 98)
Values: median (range)

Conclusion: Bone resorption is markedly suppressed compared to bone formation. Vitamin D and PTH status influence the extent of suppression of bone resorption. An assessment of bone turnover markers may allow improved titration of BPT.

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