Hyperthyroidism: Impact on bone

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Thyroid hormone is known to result in increased osteoclastic activity, resulting in negative skeletal calcium balance and osteopenia in adults. The precise geometry of this bone loss, however, has not been clear.

As readers of The Journal know from a number of recent articles, although DEXA continues to be a popular measurement of bone density in children, the modality has significant limitations. Especially in growing children, quantitative CT (qCT) has the advantage of providing more detailed data on bone geometry.

With this background, Numbenjapon et al used qCT to examine bone in 18 children with untreated hyperthyroidism. These children had preferential loss of cortical bone as determined by this methodology. The authors provide a number of testable hypotheses which might explain this observation. Regardless of the underlying physiology, their study reminds us that bone mineral loss is a common accompaniment of hyperthyroidism in children as well as adults.