4 June 2013

Growth Charts (Medical students)

The most common charts used in paediatrics are:
  • Weight-and-age
  • Height-and-age
  • OFC-and-age
  • BMI-and-age
It is not unusual for the babies to cross one centile band, up or down, in the first year of life. Babies with low birth weight tend to show ‘catch-up growth’ in the first months. Bottle fed infants tend to be heavier than breast-fed babies.

Serial measurements give information on the growth pattern. The trend or direction of the curve is more important than actual centiles. Abnormal growth is indicated by values well beyond the upper and lower centiles on a single occasion or more commonly by crossing centiles.

Compare height and weight centiles. For example, a baby is not necessarily overweight if his weight is on the 97th centile. If his height is also on the 97th centile (or close), his weight is appropriate. On the other hand, the baby may be overweight if his weight is on the 50th centile while his height is on the 3rd centile.

BMI

BMI = weight (kg)/height2 (m2)

In children the BMI should be plotted on a centile chart; weight categories are defined as follows:
  • less than 5th centile: underweight
  • 5th-85th centile: normal
  • 85-95th centile: overweight
  • above 95th centile: obese

Mid-parental height

The mid-parental height provides an estimation of the expected final height. If the child's height centile is distant from the mid-parental centile is indicative of short or tall stature.
  • For boys: Mid-parental height (cm) = Father's height + Mother's height + 12.5) divided by 2.
  • For girls: Mid-parental height (cm) = Father's height + Mother's height - 12.5) divided by 2.
Description
  1. Check personal details and if the chart is appropriate for the gender of the child.
  2. Note if the parameter is tracking along a growth curve, or crossing centiles upwards or downwards.
  3. Describe one parameter at a time, e.g. weight, and then height. For example, referring to the graph:

“Starting from the 50th centile at 3 years, the weight crossed centiles upwards to above the 95th centile at 7 years of age. During the same period the height tracked the 50th centile. At 7 years the weight is excessive for the height of the child; this is indicative of obesity.”

Interpretation
 
Students should familiarize themselves with the following growth patterns:
  • Normal growth
  • Familial short stature
  • Failure to thrive (malnutrition: inadequate intake, reflux; malabsorption: CF, coeliac; chronic disease: IBD, renal failure, etc)
  • Obesity
  • Growth hormone deficiency (as well as hypothyroidism, cortisol excess).
  • Constitutional delay in growth and puberty
  • Turner's Syndrome (ask about delayed puberty and stigmata)
  • Macrocephaly and hydrocephalus
  • Microcephaly