Reference ranges for knee height in Argentine children and adolescents aged 2 to 18 years.

OBJECTIVES: Measurement of height is essential in the anthropometric assessment of growth and nutritional status. In some conditions, height measurement may be difficult or impossible. Proxy measurement such as knee height (KH) have been proposed to predict stature in such cases, but reference percentile ranges and charts for healthy, well-nourished children are currently unavailable. This study was designed to develop sex-specific KH reference percentile ranges and charts in Argentine children ranging from 2 to 18 years of age. METHODS: We collected and analyzed cross-sectional data for KH from 861 Argentine children and adolescents aged 2 to 18 years. Generalized additive models for location, scale, and shape were used to calculate semiparametric smoothed percentile reference ranges, and charts by age and sex. Linear regression and correlation analyses were performed to know the association between KH and height. RESULTS: The new reference ranges show that KH growth rose sharply until puberty. Peak KH velocity occurs 1 year earlier than peak height velocity. At puberty KH growth decelerated rapidly in females and increased slightly until 15 years and plateaued at this age, while it had a more gradual deceleration in males up to 11 years old, later increased slightly until 17 years and plateaued at this age. The correlation coefficient between height and KH was r = 0.98 for both sexes (p < .001). CONCLUSIONS: The new reference percentile ranges for KH measures for healthy children and adolescents provide a useful growth and nutritional assessment tool in a wide variety of settings. KH has a strong agreement with stature.

Development of regression equations for estimating height and weight using body segments in Argentine children.

OBJECTIVES: Body weight and height measurements are essential in children for assessing growth and nutrition, for the calculation of medication doses, and for the effectiveness of medical interventions. When direct measurements cannot be made, segmental measures can be used to estimate weight and height. The equations available to estimate height and weight, however, are limited. The aim of this study was to use segmental measures to develop equations for use in pediatric clinical practice. METHODS: A cross-sectional study design was used to collect data from 861 healthy children (484 females and 377 males) ages 2 to 18 y to develop equations for estimating weight and height from midarm circumference (MAC) and knee-heel height (KH), respectively. A multi-linear regression model was used to develop the equations. RESULTS: The high correlation between MAC and the actual weight and KH and height indicates strong agreement. Four equations were developed to estimate weight and height using segmental measures. 1. To estimate weight from MAC for females: W = 2.37 × MAC + 1.64 × age (y) - 28.28. 2. To estimate weight for males: W = 2.54 × MAC + 1.82 × age (y) - 32.73. 3. To estimate height from KH for females: H = 2.88 × KH + 0.15. 4. To estimate height from KH for males: H = 2.73 × KH + 0.21. CONCLUSIONS: MAC and KH can be used for estimation equations for weight and height with a very good predictive power. Sex and age were significant covariates in estimating weight. To predict height, only sex was needed to fit the model.