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Seasonality in lower leg length velocity in prepubertal children
L Gelander1, J Karlberg, K Albertsson-Wikland
1Department of Pediatrics, University of Göteborg, Sweden.
Insights
Short-term lower leg length (LLL) measurements poorly predict annual growth. Seasonal variations in LLL velocity occur simultaneously with height velocity, impacting growth predictions.
Area of Science:
- Pediatric Endocrinology
- Human Growth and Development
- Biometric Analysis
Background:
- Annual growth prediction using short-term measurements is challenging.
- Previous studies have not identified seasonal variations in lower leg length (LLL) velocity.
Purpose of the Study:
- To investigate if seasonal changes in LLL velocity explain the poor correlation between short-term measurements and annual growth.
- To longitudinally analyze short-term growth in prepubertal children.
Main Methods:
- Longitudinal study of 50 prepubertal children with normal growth.
- Height measured every 4 weeks; LLL measured every 1-2 weeks.
- Analysis of seasonal variations in height and LLL velocity.
Main Results:
- Significant seasonality observed in both mean monthly height velocity (autumn vs. spring) and LLL velocity.
- LLL velocity showed a 31% seasonal change, while measurement error was 7-8%.
- Correlation between monthly LLL velocity and annual height velocity was low (r = 0.27).
Conclusions:
- Significant, simultaneous seasonality exists in both height and LLL velocity.
- LLL seasonality is a novel finding and must be considered in growth studies.
- LLL measurements are unreliable for predicting annual height velocity due to seasonal fluctuations.
Abstract:
Despite low measuring error, annual growth is poorly predicted by short-term measurements of the lower leg. In order to study if this low correlation can be explained by seasonal changes in lower leg length (LLL) velocity, we followed short-term growth longitudinally in 50 prepubertal children with normal height and growth velocities. Height measurements were performed at 4-week intervals and LLL measurements at 1-2 week intervals. Analysis of annual growth showed seasonality in the monthly mean height velocity values: 5.06 (SD 5.02) cm/year during the autumn and 8.15 (SD 5.22) cm/year in the spring. Similarly, the monthly mean LLL velocity values changed from 1.80 (SD 1.07) cm/year in the autumn to 2.63 (SD 0.92) cm/year in the spring. The correlation between monthly LLL and annual height velocity was low (r = 0.27). The technical error of the LLL measurement was 7-8% of the mean monthly LLL velocity, while the mean values changed by 31% over the seasons. The annual height velocity was virtually independent of the variation in growth rate over the seasons. It is concluded that there is significant seasonality both in height and LLL velocity and that it takes place at the same time for both measures. Seasonality in LLL has not been reported previously and must be considered when studying short-term growth, for example when LLL is used for prediction of annual height velocity or when a short-term treatment effect is examined using LLL.