Bone Abstracts

Introduction: Lymphoblastic leukemia is the predominant form of childhood malignancies with survival rates of >80%. Late effects of cancer and treatment can affect endocrine function and may account for acute and chronic impairment of bone health.

Aim and design: To assess bone health in pediatric patients after therapy for lymphoblastic leukemia we initiated a clinical trial investigating clinical and biochemical parameters of growth, puberty, bone turnover, and vitamin D metabolism, as well as bone densitometry using DXA scans in a subgroup of patients. Additionally a questionnaire was developed assessing life style parameters including calcium and vitamin D intake and levels of physical activity. Patients (n=90) were treated for leukemia according to applicable ALL-BFM protocol (1994–2011) and recruited at follow-up visits at the Children’s Hospital Essen.

Results: 39 of the 90 patients were female. Mean (range) chronological age (CA) was 11.47 (3.8–20.9) years, age at diagnosis was 6.9 (0.8–16.9) years, height SDS −0.04 (−3.69 to 2.72), BMI SDS 0.48 (−4.12 to 2.74), SDS for Tanner stage 0.22 (−3.2 to 3.5). Mean serum 25-OH vitamin D levels were 17.34 (1–62.6) ng/ml, 1.25 (OH)2 vitamin D levels were 60.2 (13–158) ng/l, BAP was 119.9 (18.3–283) U/l, PTH 46.7 (9.6–159.8) pg/ml, N-telopeptide in urine 908.8 (21–3000) mmol/mg creatinine and calcium:creatinine ratio in urine was 0.12 (0.01–0.4) mg/mg. Mean calcium intake/week was 5.64 g (1.2–10.5), vitamin D intake: 15.4 μg (0.22–46.6). Average screentime was 1.9 (0–5) h/day, average daily activity: 5.12 h/day. Mean age corrected Z-score in DXA scans was −0.55 (−3.3 to 2.1, n=30).

11% of the patients experienced fractures after chemotherapy, 3 patients reported frequent fractures. Vitamin D deficiency (25 OH-vitamin D<20 ng/ml) was observed in 68% and secondary hyperparathyroidism in 17%. 15% reported bone pain after physical activity. Male and female patients did not differ significantly with respect to biochemical or clinical findings. There was a trend to lower height SDS in boys in this cohort. Accordingly mean bone age (BA) was delayed in boys (Delta BA/CA: −1.7 (−5.1 to 0.33) years. Osteopenia (Z-score <−2) was detected in 15% of the patients screened. No correlation between Z-scores and N-telopeptide levels in urine or total dosage of prednisone, dexamethasone or methotrexate was observed.

Conclusion: Bone health is impaired in some patients after treatment for childhood leukemia. Clinically this is reflected in bone pain and/or fractures. Prediction or identification of children at risk is difficult and requires assessment of additional clinical, biochemical and radiological measures. As previously reported, vitamin D and calcium deficiencies are frequent findings in this group and adequate monitoring and supplementation is recommended.