Bone markers after total body irradiation in childhood

Abstract

Total body irradiation (TBI) can cause short stature because of decreased growth hormone (GH) and skeletal abnormalities. To evaluate the plasma concentrations of markers of bone formation (osteocalcin and procollagen type 1 amino-terminal propeptide, P1NP) and resorption (carboxy-terminal telopeptide, CTX), in patients (n=65) who had been given TBI at 6.6+/-0.4 years were evaluated at 9.8+/-0.4 years. Patients given single 10 Gy or fractionated 12 Gy TBI had similar characteristics, except that plasma insulin-like growth factor (IGF-1) was lower in those given a single 10 Gy. Seven had lower osteocalcin and two had higher CTX than controls. Bone markers (as zs) were positively correlated (osteocalcin with P1NP, rho=0.42, P=0.0007; osteocalcin with CTX, rho=0.3, P<0.02), but not P1NP with CTX. Plasma osteocalcin and CTX were also positively correlated with plasma IGF-1, but not with growth rate during the first year on GH (n=28). Adult height was -2.5+/-0.2 s.d.s. (n=49). Those irradiated when young (P=0.0002) or given single TBI lost more height between TBI and adult height. Most TBI patients had normal bone formation and resorption markers. Thus, impaired bone turnover is probably not the cause of their short stature and poor response to GH.