Letter to the Editor: “Calcium and Bone Turnover Markers in Acromegaly: A Prospective, Controlled Study”

We thank Constantin et al. (1) for sharing their important study about changes of calcium and bone turnover markers in acromegaly. In this study, 44 patients were collected from a tertiary referral center, including 22 patients with acromegaly (as the acromegaly group), whereas the other 22 patients with nonfunctioning macroadenomas were seen as the control group. However, there are some concerns with this study.

First, patients in the control group who had macroadenomas had lower hormone levels than did patients with nonfunctional microadenomas or healthy people, as a result of tumors always suppressing the pituitary, which showed indeed that 54.5% of patients in the control group in this study had hypogonadism. Because bone metabolism under hypogonadism or any other kind of hypopituitary condition is always impaired, it may be more reasonable to add a nonfunctional microadenoma or normal group matched with sex and age to clarify the real impact of acromegaly on bone turnover and thus make the data more comparable.

Second, there was one primary hyperparathyroidism patient in the acromegaly group, indicating that two endocrine gland disorders were involved. It should be highly considered that the patient might have multiple endocrine neoplasia other than simple acromegaly (2, 3). Moreover, serum calcium and bone turnover markers are expectedly more influenced by a high PTH level, which may confuse the effect of simple acromegaly. We suggest that this case should be eliminated when doing the analysis.

Finally, it has always been a concern that calcium and vitamin D supplementation may play a role in bone turnover markers. Therefore, for patients who used calcium and vitamin D supplements from the start of the study to its end, the dosage should be specified and final analysis should consider these patients as a subgroup.

Acknowledgments

This work was supported by National Natural Science Foundation of China Grants 81000361 and 81471091.

Disclosure Summary: The authors have nothing to disclose.

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