Bone Mineral Measurements in Neonates-Reply

In Reply.—As noted in our article¹ and as described by Dr Nord, the photon absorptiometer marketed by the Norland Corporation, Fort Atkinson, Wis (and until recently the only one used for assessing small infants) has indeed been modified. Our findings obscure the interpretation of virtually all published studies using photon absorptiometry in small infants, but they do not reflect the reliability of the model 278-A Norland Bone Densitometer. Dr Nord's statements about this model are encouraging. However, as for other evaluation tools, adequate reliability should not be assumed until the manufacturers or investigators answer all important questions about their reliability studies. One should know whether only "representative" scans were included and whether scans without clearly discernible bone edges were excluded when reliability was calculated. Was the instrument further modified by the investigators, or were high-intensity radiation sources used to improve reliability? Were low-birth-weight infants with rickets or severe osteopenia