Bone Abstracts

Introduction: Treatment in thyroid function disorders, which lead to clinical hypothyroidism, is replacement with levothyroxine. We aimed to investigate the effect of long-term levothyroxine therapy on vitamin D metabolism and bone mineral density in children.

Materials and methods: Twenty-seven children with hypothyroidism receiving levothyroxine therapy (M/F: 13/14, mean age, 12.1±0.7 years) and 21 healthy controls (M/F: 13/8, mean age, 11.8±0.5) were enrolled. Calcium, phosphorus, alkaline phosphatase, parathormone and 25-hydroxy vitamin D levels were measured from serum specimens collected from the study and control groups. DEXA scans were performed and Z-scores determined.

Results: Mean duration of levothyroxine treatment was 7.7±0.5 months. Serum vitamin D levels were significantly lower in the study group (17.1±7.6 ng/ml) compared to the control group (23.6±7.8 ng/ml) (P=0.006), but short-term treatment did not appear to have an effect on BMD Z-scores (P>0.05).

Conclusion: Long-term levothyroxine therapy can affect vitamin D levels and impair bone health. Accordingly, bone mineral density analysis would seem to be useful in long-term.