University of Arkansas for Medical Sciences Division of Endocrinology and Metabolism Little Rock, Arkansas 72205
To the editor:
Roemmich et al. (1) report interesting data using inappropriate terminology. Bone is made in two stages; matrix is formed first, and about 2 wk later (in children) it begins to mineralize (2); the delay is longer in the adult skeleton (3). The process of adding mineral to matrix is referred to as "bone mineralization." It is important that this term not be used for the quite different process of adding bone to the growing skeleton, a confusion that arose because the measurement of bone mass in vivo is usually based on measuring the amount of mineral. This is possible because in the absence of rickets or osteomalacia the degree of mineralization of matrix varies between fairly narrow limits, so that for the most part mineral mass is a reasonable estimate of bone mass. An increase in mineral mass does represent bone mineralization in two circumstances: the treatment of osteomalacia (4) and the completion of secondary mineralization when bone turnover is reduced and bone age increased (5), but neither of these applies to the growing skeleton. Whatever its role in the control of bone mass, no effect of leptin on bone mineralization has been demonstrated.
Footnotes
1 Address correspondence to: A. Michael Parfitt, University of Arkansas for Medical Sciences, Division of Endocrinology and Metabolism, 4301 West Markham Street, Slot 587, Little Rock, Arkansas 72205.
A response to this letter was invited, but the authors of the original article chose not to provide one.
Received June 24, 2003.
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