Measuring Growth

A child should be measured at every visit with their pediatrician. Growth rate is best determined by measurements done 3-6 months apart. Incorrect measurements are responsible for numerous inappropriate referrals for short stature. Furthermore, the incorrect measures can make it difficult to determine the effects of growth promoting medications,

An accurate measurement of infant length is extremely difficult to perform and always requires two adults. The child should be laid flat on a surface with a device that has one plate horizontal to the plane of the top of the head of the child and another plate horizontal to the feet. Frequently using a mark on a paper cover can be misleading since the paper can be crumpled and bent.

The measurement of a patient older than 2 years is done with the child standing. There can be a 1 to 2 cm difference when switching from laying to standing measurements. Shoes must be removed. A stadiometer is used to measure the height.

Determination of arm span and the upper-to-lower ratio are also useful in evaluation of short stature or delay of puberty. The arms span is done with patient standing with their back to the wall and arms horizontally. The measurement is from one outstretched fingertip to the other. Generally the arm span measurement should be close to the measurement of height. If the arm span is less than height then a chondrodystrophy may be limiting bone growth. If the arms plan is longer than height then abnormalities of spinal growth may be a possibility. The upper lower ratio is from the top of the symphysis pubis to the floor. The upper is determined by subtracting the lower from the total height. A decreased upper-to-lower ratio is seen in Kleinfelter syndrome. An increase in the ratio is seen in hypothyroidism and chondrodysplasias.

Bone age is more closely correlated with certain developmental landmarks than with chronological age when determining if there is delayed or advanced puberty. A bone age test does not diagnose a condition but rather gives support for a condition under consideration. The bone age is determined by x-rays of the left hand and wrist, then compared to the standards in the Greulich and Pyle atlas in most US facilities. Europeans use the Tanner Whitehouse (TW) method. Delayed bone age is written in standard deviations from the average reading for chronological age. These standard deviations change with patient age.