Tanner’s formula, measure bone maturation

Monitoring how and how far a person's growth will go is important and we have ways of knowing their genetic stature to assess whether or not growth is optimal.

Bone maturation

The growth and maturation of the individual are two biological processes closely related, but not always parallel throughout childhood and adolescence. That is, we can have slow growth and accelerated bone maturation and vice versa. Each child has its own maturation “tempo”, so chronological age is not necessarily an indication of the degree of biological maturation.

The only accepted indicator of maturation, valid from birth to adulthood, is bone age. agree that the estimate of bone age approximates and reflects the biological age of the child. The downside is that this method is not valid in the first year of life. In infants other scales should be used.

When pediatricians assess a child's height and suspect that it is significantly smaller or larger than expected, we must complete the growth study with an evaluation of bone maturation. This allows us to see if there is, what will improve over time, or if there is a bone maturation according to the age of the child or higher that alerts us that this size is lower than genetically expected. This parameter is useful, among others, to decide or not to start a treatment for short stature.

Tanner's formula

One of the most widely used formulas to assess bone maturation is the Tanner-Whitehouse formula. It is based on the application of scores or "" maturity in the different hand and wrist bones.

How does it apply?

• Performing one of the non-dominant hand and wrist.
• Each bone in the hand and wrist is classified into 8-9 stadiums to which a score is assigned. The total score represents a fairly accurate figure. It has the downside of having been created for a middle-class English and Scottish population in the 1950s and 1960s.

Despite being a widely used indicator, recent work in the rural population of southeastern Spain seems to indicate that the prediction of target height by the Tanner method underestimates the final height in young people. This study shows that the formula for the target size it predicts a height much lower than the final height of the individuals, this underestimation being greater in girls than in boys.

The role of genetics in growth

The final height that an individual will reach is genetically determined by various genes, but it can be modulated by environmental or extragenetic factors such as diet or chronic diseases in the first years of life.

Pediatricians calculate genetic size and compare it with what we measure in the consultation. This allows us to keep track of the child's health, assess the nutritional status or suspect if there is an underlying health problem (such as allergy to cow's milk protein, celiac disease or growth hormone deficiency). In addition to this clinical utility, the growth of a population it is one of the best economic and development indicators. For example, we are taller than our grandparents, among many factors, because we receive a better diet and we do not experience wars or postwar periods that limited proper nutrition in a large sector of the population.

Predict the final size or target

Predicting a child's final height before the end of growth is a very useful parameter that can be reliably obtained in a variety of situations. This prediction is based on three principles:

• The final size It depends largely on genetics and inheritance from our parents. It has a weight of up to 75%.
• From 18 months the child is in the lane or percentile that he will follow until the end of his growth period.
• Bone maturation It is the most accurate indication to assess chronological age and to know the percentage of final height that has been reached at a given moment in the child's development.

Normally the daily height is calculated from the average parent's height. This will give us the final prediction of the height that the child will reach.

• The only accepted indicator of maturation, valid from birth to adulthood, is bone age. Pediatricians and endocrinologists agree that the estimate of bone age approximates and reflects the biological age of the child.
• One of the most used formulas to assess bone maturation is the Tanner-Whitehouse formula.
• The Tanner formula is applied by taking an X-ray of the non-dominant hand and wrist. It has the downside of having been created for a middle-class English and Scottish population in the 1950s and 1960s.

Pediatric specialist