Bone Age Delay in X-linked Hypophosphatemia

TL;DR

This study finds that children with X-linked hypophosphatemia have delayed bone age, with males showing more significant delays, and compares height prediction methods in these patients.

Contribution

The study provides new insights into bone age delays and height prediction accuracy in children with X-linked hypophosphatemia.

Findings

Males with XLH showed a greater bone age delay (1.2 years) compared to females (0.4 years).

Height prediction methods overestimated adult height in XLH patients, with Bayley-Pinneau overestimating in males and Tanner-Whitehouse in females.

Over 50% of males and 21% of females had a bone age delay of 1 to 2 years.

Abstract

Bone age (BA) assessment and prediction of adult height (AdHt) has not been well studied in children with X-linked hypophosphatemia (XLH).

To assess BA and its utility in height prediction in children with XLH.

Retrospective, cross-sectional, and longitudinal assessments of BA using 2 standard methods in children with XLH. Mean values were used to calculate predicted adult height (PAH), which was compared to final or near-final AdHt in patients who were at or near the end of growth.

Academic medical center.

Fifty-six children with XLH.

None.

BA, PAH.

Initial radiographs demonstrated BA delay (chronologic age–BA) of 1.2 ± 1.0 (mean ± SD) years in males and 0.4 ± 1.0 years in females (greater delay in males, P < .05). Fifty-eight percent of males and 21% of females were delayed 1 to 2 years; 11% of males and 9% of females were delayed more than 2 years. For 4 males with no prior orthopedic surgeries, mean AdHt was 171.2 ± 5.3 cm; PAH was 176.3 (±11.7) cm using Bayley-Pinneau methods and 173.0 ± 6.8 cm per Tanner-Whitehouse methods. For 15 females without prior orthopedic surgeries, AdHt was 155.9 ± 5.2 cm; PAH was 156.0 ± 6.8 cm (Bayley-Pinneau) or 161.6 ± 4.2 (Tanner-Whitehouse, which differed from AdHt, P < .005).

BA is delayed in children with XLH but more strikingly so in males. Height predictions were within a range typically used in healthy children (±2 inches). The Bayley-Pinneau method appears to modestly overestimate AdHt in males, whereas Tanner-Whitehouse overestimates AdHt in females.

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