Paediatrics: Assessment of growth

Assessment of growth

Growth must be measured accurately. Equipment used to measure weight and height must be regularly maintained, checked, and calibrated. Ideally, growth measurements should be carried out by someone specifically training and experienced in measurement techniques (e.g. an auxologist). This will minimize measurement error.

Assessment of height

·  From birth to age 2yrs, length is measured horizontally using a specifically designed measuring board (e.g. Harpenden Neonatometer). Two people need to ensure that child is lying straight with legs extended.

·  In children, aged ≥2yrs, standing height is measured against a wall-mounted or free-standing stadiometer. A specific technique is required, with the person measuring applying moderate upward neck traction to the child’s head with the child looking forward in the horizontal plane.

·  Measurement of sitting height using a modified stadiometer and calculation of the leg length (standing height minus sitting height) allows an estimate of upper and lower body segments and body proportion.

Growth data interpretation

Weight and height measurement data should be plotted on a simple sex and age range appropriate standard growth centile chart (e.g. the UK 1990 Growth Reference charts). A UK-WHO growth chart for children from birth to 4yrs of age has been developed based on the WHO child growth standards. These describe optimal growth of healthy breast-fed children. Previous UK growth charts based on data from studies on breast- and formula-fed children, do not reflect normal weight fluctuations of breast-fed infants in first few weeks (see Fig. 13.1). Height measurements should be plotted on specific population growth charts where necessary or applicable, e.g. Turner’s syndrome; Down’s syndrome.

Single growth measurements should not be assessed in isolation from other previous measurements. Serial measurements are used to show a pattern of growth and to determine growth rate. To minimize error in the assessment of growth rate, calculation of height velocity (cm/year) should be taken from measurements a minimum of 6mths apart, ideally using the same equipment and by the same person.

Final height and target height

Final height is the height reached after the completion of puberty and is estimated to be achieved when growth velocity has slowed to <2.0cm/ year. This can be confirmed by finding epiphyseal fusion of the small bones of the hand and wrist on assessing the bone age X-ray.

Final height is largely genetically determined. A target height range can be estimated in each individual from their parent’s heights, first calculating the mid-parental height (MPH).

MPH (boys) = [(Mother’s ht (cm) + Father’s ht (cm))/2] + 6.5cm

MPH (girls) = [(Mother’s ht (cm) + Father’s ht (cm))/2] – 6.5cm

Target height range = MPH 9 10cm

Bone age

This is a measure of skeletal maturation, which can be assessed by the appearance of the epiphyseal centres of the long bones. Conventionally this is quantified from X-rays of the left hand and wrist, with either com-pared with standard radiograph images (e.g. Gruelich and Pyle method) or assessed using an individual bone scoring system (Tanner–Whitehouse methods).

The difference between bone age (BA) score and chronological age at the time of assessment may be used as an estimation of the tempo of growth. The BA may also be used as an indicator of the likely timing of puberty, which usually starts when BA is around 10.5yrs in females and 11.5yrs in boys. The relationship between BA and age of onset of menarche is more robust.

Girls usually reach skeletal maturity at a BA of 15.0yrs and boys when BA is 17.0yrs. The BA can therefore be used as an estimation of the remaining growth potential and can be used to predict final adult height.