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Screening for short stature in childhood is useful for identifying growth disorders such as growth hormone deficiency or Turner's syndrome. However, as with any screening instrument its performance needs to be quantified. 1 The UK height reference 2 ensures a low false positive rate because its 0.4th centile screens in only four children/1000, but the corresponding sensitivity is poor. 1 In particular, short children of tall parents are likely to be missed.
Midparental height, the average of the two parents' heights, is the traditional approach to adjusting for family size. Target height, derived from midparental height by adjusting for the child's sex, predicts the child's height as an adult. A recent paper 3 investigated target height in a Swedish growth study, but target height has been criticised 4 because it does not adjust for regression to the mean.
An alternative use of midparental height is to relate it directly to the child's current height, which avoids the concept of target height in adulthood. Tanner and colleagues 5 published a chart that adjusts child height, expressed as a centile, for midparental height, and so identifies children who are short within their family. This more direct approach is preferable, because it focuses on the child's height now rather than as an adult. It also adjusts for regression to the mean.
However, adjusting for midparental height is not entirely straightforward. It implies that very short children are of appropriate height if their parents are short, which might not be the case. What is needed is a combined approach, to identify not only very short children, irrespective of their parents' height, but also short children whose parents are tall.
A recent practical problem with midparental height is the single parent family, where only one of the two parents can be measured. However, it should be recognised that the height of one parent alone provides useful information about the child's height. In addition, adjustment can be made for sibling height if there is a sibling close enough in age. This also assumes, as does the midparental height adjustment, that the rest of the family does not suffer from a growth disorder.
To be able to deal with the various familial alternatives-one parent and/or the other, with or without a sibling-a...