What is a bone age test?
A bone age test is a diagnostic imaging procedure that helps medical professionals assess the maturity of a child's bones. Unlike chronological age, which is based on a person's birth date, bone age reflects how much the skeleton has developed and is used to predict growth potential. It is most often performed in children and adolescents who are experiencing abnormal growth patterns, delayed or early puberty, or other endocrine disorders. The standard method involves taking a single X-ray of the child's left hand and wrist because these areas contain numerous bones and growth plates that provide a comprehensive view of skeletal development.
The standard procedure for a bone age assessment
Consulting a healthcare provider
The first step to getting a bone age check is to consult with a healthcare provider, such as a pediatrician or a pediatric endocrinologist. The doctor will discuss your child's growth concerns, medical history, and any symptoms related to delayed or accelerated development. Based on this evaluation, the doctor will determine if a bone age assessment is necessary and provide a referral for the test. For adults, a bone age check is generally not performed, as skeletal maturity is complete once growth plates have fused. Instead, adults concerned about bone health would typically receive a bone density scan.
During the radiology appointment
When you arrive at the radiology department, your child will be prepped for a quick and painless X-ray. The process is very straightforward and usually takes only a few minutes.
- Your child will be asked to sit or stand and place their left hand and wrist on a flat table or plate.
- They will need to keep their hand and fingers still and spread out for a few seconds while the image is taken.
- To minimize radiation exposure to the rest of the body, a lead apron may be used to cover the torso.
The test uses a very small, safe amount of radiation, significantly less than a standard chest X-ray.
Interpreting the results
After the X-ray is complete, a radiologist analyzes the image and compares it to a standard set of X-ray images, known as an atlas, which represents the typical bone development of children of various ages and genders. The bones of the hand and wrist, including the small carpals and the growth plates at the ends of the long bones, are evaluated for shape, size, and level of mineralization. The radiologist then assigns a bone age based on which atlas image is the closest match. The results are sent to the referring doctor, who will discuss the findings with you.
Who typically needs a bone age check?
Doctors may recommend a bone age assessment for children and adolescents for a variety of reasons:
- Growth concerns: For children who are significantly taller or shorter than their peers, or whose growth rate seems abnormal.
- Delayed or advanced puberty: To investigate early onset of puberty (precocious puberty) or delayed puberty.
- Chronic illnesses: Conditions such as chronic kidney disease or juvenile diabetes that can impact a child's growth and development.
- Hormonal disorders: To diagnose and monitor conditions affecting hormones, such as growth hormone deficiency or hypothyroidism.
- Genetic conditions: For conditions like Turner syndrome, which can affect bone growth.
- Nutritional deficiencies: In cases of severe malnutrition that can impede bone development.
- Orthopedic planning: To guide the timing of certain surgical or orthodontic procedures.
Bone age vs. bone density (DEXA): A comparison
It is common for people to confuse a bone age assessment with a bone density scan (DEXA), but they serve different purposes. Here's a quick comparison:
| Feature | Bone Age Test | Bone Density (DEXA) Scan |
|---|---|---|
| Primary Purpose | Measures the skeletal maturity and developmental stage of bones. | Measures the density or strength of bones to assess risk of fracture and osteoporosis. |
| Primary Patients | Children and adolescents with growth concerns. | Adults, especially postmenopausal women and older men. |
| Body Part Scanned | Typically the left hand and wrist. | Typically the hips and spine. |
| Results | Yields a 'bone age' in years, which is compared to chronological age. | Yields a T-score (adults) or Z-score (children) to quantify bone mineral density. |
| Interpretation | Radiologist compares the X-ray to a standard atlas to assess bone development stages. | Evaluates mineral content in the bone for conditions like osteopenia or osteoporosis. |
Understanding your child's bone age results
Once the X-ray is analyzed, the results are compared to your child's actual (chronological) age to determine if their skeletal maturity is normal, advanced, or delayed. A difference of more than two standard deviations from the chronological age is generally considered significant.
- Normal results: A bone age that aligns with the chronological age suggests that the child is growing at an average rate and is on track developmentally.
- Delayed bone age: This means the skeleton appears younger than the child's actual age and can be linked to conditions such as growth hormone deficiency, hypothyroidism, or prolonged malnutrition.
- Advanced bone age: An older-looking skeleton can suggest accelerated development, often seen in cases of precocious puberty or certain hormonal imbalances.
Based on these findings, the doctor can develop a targeted treatment plan or recommend further diagnostic testing.
Conclusion: Navigating the bone age assessment
Knowing how to get your bone age checked is the first step toward understanding and addressing potential growth abnormalities in a child. The procedure, involving a simple hand and wrist X-ray, is a crucial diagnostic tool for pediatricians and specialists. By accurately assessing skeletal maturity, healthcare providers can diagnose conditions that affect growth, monitor treatments, and even help predict a child's final adult height. For adults, the focus shifts to bone density, but for a growing child, a bone age assessment offers invaluable insights into their developmental trajectory.
For more in-depth information about bone health and development, you can visit the National Institutes of Health (NIH) website.
Key considerations for bone age assessment
- Pediatric focus: Bone age assessments are primarily used for children and adolescents to evaluate growth and skeletal maturity.
- Hand and wrist X-ray: The standard procedure uses a low-radiation X-ray of the left hand and wrist to examine the growth plates.
- Referral is required: You must consult with a healthcare provider who can order the test based on specific growth concerns.
- Not the same as DEXA: A bone age test is different from a DEXA scan, which measures bone density for osteoporosis risk in adults.
- Valuable diagnostic tool: Results can help diagnose conditions like hormonal disorders or precocious puberty by revealing developmental discrepancies.
- Interpretation by a specialist: A radiologist or pediatric specialist interprets the X-ray by comparing it to a standard atlas of bone development.
Frequently asked questions about bone age
Q: What is a bone age study? A: A bone age study, or skeletal maturity assessment, is a radiological procedure, usually an X-ray of the hand and wrist, used to determine the maturity of a child's bones and estimate their growth potential.
Q: Who needs to get a bone age checked? A: A bone age check is typically recommended for children or adolescents who have abnormal growth patterns, delayed or early puberty, or other medical conditions affecting skeletal development.
Q: Is there an age limit for a bone age test? A: Bone age tests are most useful for children and adolescents. For adults, whose growth plates have fused, the test is not performed. Instead, a bone density scan (DEXA) is used to assess bone health.
Q: How is a bone age X-ray performed? A: During the test, a radiologist will take a quick X-ray of your child's left hand and wrist. Your child will wear a lead apron for protection, and the process is painless and takes only a few minutes.
Q: How does a doctor interpret the results of a bone age test? A: The X-ray image is compared to a standard atlas of bone development to find the closest match. The bone age assigned is the chronological age associated with that standard image in the atlas.
Q: What does it mean if the bone age is advanced or delayed? A: An advanced bone age might suggest precocious puberty, while a delayed bone age could indicate growth hormone deficiency or other underlying medical conditions.
Q: Can a bone age test predict a child's height? A: Yes, a bone age assessment can be used in combination with a child's current height and growth rate to predict their final adult height.
Q: Is there any risk involved with the X-ray? A: The X-ray uses a very low dose of radiation and is considered safe for most people. However, it is not recommended during pregnancy.
Q: What should I do if my child's bone age is abnormal? A: You should follow up with your child's doctor or a specialist like a pediatric endocrinologist to discuss the results and potential next steps, such as further testing or treatment.
