Children with classic congenital adrenal hyperplasia (CAH) may grow rapidly during childhood but stop growing earlier than expected. This can keep them from reaching their target height range. The target height range is an estimate of adult height based on their parents’ heights.

People with classic CAH are often shorter as adults than expected, but every person is different. Final height can be influenced by several factors, including hormone levels, treatment, and the timing of puberty.

In this article, we’ll take a closer look at research on predicting final adult height in children with CAH and the factors that can influence how tall they grow.

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What the Research Says About CAH and Height

A child with CAH may have a harder time reaching their target adult height range because of high levels of androgens (sex hormones that help drive traits such as body hair and muscle growth).

High levels of androgens cause bones to mature faster. Growth plates are areas near the ends of bones that allow them to grow. When bones mature too quickly, these plates may close early. Once they close, the child won’t grow any taller.

Several small studies have tracked the growth of children with CAH through final adult height.

Classic CAH and Height

Multiple studies have examined final height among children with classic CAH. Children with classic CAH may reach an adult height near the lower end of the range expected based on their parents’ heights.

Researchers note that glucocorticoid treatment, such as hydrocortisone, may contribute to shorter adult height. For children with CAH, doctors must carefully balance the benefits and risks of glucocorticoid doses during different stages of growth.

Nonclassic CAH and Height

Research findings on untreated nonclassic CAH have been mixed. Some studies have found that most children reached their target height range, whereas another found that most had a final height below their target range.

Research generally shows that nonclassic CAH has less effect on final height than classic CAH. Short adult height is not a consistent finding in people with nonclassic CAH.

How Doctors Predict a Child’s Final Height

Research suggests that parental height accounts for 60 percent to 70 percent of a child’s final height. Health experts often use Tanner’s formula to estimate a child’s target height range from the heights of both parents, a calculation known as the midparental target height.

To predict the final adult height of a child with CAH, endocrinologists consider the heights of the parents and the child's bone age.

Doctors and researchers may take more than just parental heights into account while calculating the predicted final height range of children with CAH. For example, they may use the Bayley-Pinneau method, which also considers the child’s bone age (how mature their bones are).

Children with CAH often have an advanced bone age, which means their bones are maturing faster than expected and they may have less time left to grow.

However, height predictions based on bone age may not always be accurate for children with classic CAH. Some studies have found that children reached a different adult height than originally predicted.

Factors That Influence a Child’s Height Growth With CAH

Health experts have identified several factors that may influence growth and final adult height in children with CAH. These factors may help doctors estimate whether a child is likely to reach their target height range.

Bone Age

In children with CAH, high androgen levels can cause bone age to advance faster than actual age. Bone age is a measure of how mature the bones are. This can shorten the time a child has to grow.

CAH specialists may monitor bone age, growth, and hormone levels during childhood and adjust treatment as needed.

Onset of Puberty

Children stop growing taller after their growth plates close near the end of puberty. In some children with CAH, long-term exposure to high androgen levels can trigger early puberty and cause growth to stop sooner.

If your child reaches puberty too early, their endocrinologist may prescribe a gonadotropin-releasing hormone (GnRH) agonist, a medication that pauses early puberty. This treatment may help protect adult height in some children.

Growth hormone may also be considered in select cases, but it is not routine treatment for CAH.

Obesity Prevention

Children with CAH have an increased risk of developing obesity from an early age. In children, obesity is diagnosed using body mass index (BMI), a calculation based on weight and height, compared with other children of the same age and sex. A high BMI is often linked with excess body fat that may affect health.

Higher body weight may be linked to earlier puberty and can affect hormone levels and growth. Your child’s care team can offer guidance on healthy habits without blame or restrictive dieting.

Appropriate Treatment

People with classic CAH are often shorter as adults than expected, but carefully managed treatment may support healthier growth.

However, research suggests that optimizing CAH treatment may lead to optimal height outcomes for children with CAH. It’s important to work closely with an endocrinologist who can effectively treat your child’s CAH as they get older while tracking their hormone levels.

Glucocorticoid steroids are a key treatment for children with CAH for children with classic CAH because they replace cortisol that the adrenal glands don’t produce in sufficient amounts. Steroids also help reduce blood androgen levels in children with CAH.

However, high doses of glucocorticoids can slow a child’s growth. A newer class of medications called corticotropin-releasing factor (CRF) type 1 receptor antagonists may be used along with glucocorticoid replacement to help control androgen levels and may allow some people to reduce their glucocorticoid dose.

For some children who start puberty early or are predicted to be much shorter than expected, an endocrinologist may discuss treatment with a GnRH agonist or growth hormone. The best approach depends on the child’s growth, bone age, and overall health.

Work With Your Child’s CAH Specialist

No matter your child’s current age, it’s important to work closely with their CAH specialist. This specialist can monitor your child’s growth and development and manage their CAH over time. Your child’s healthcare team can also track their hormone levels and adjust treatment based on the results of lab tests for CAH.

If you have concerns about your child’s rate of growth and development, let their endocrinologist know. Appropriate CAH management can support healthy growth and may improve your child’s chances of optimizing their final height in adulthood.

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