Interview With Dr. Catherine Gordon on Idiopathic Juvenile Osteoporosis

In Honor of Osteoporosis Awareness and Prevention month we'd like to talk about bone loss in children with Dr. Catherine Gordon. Dr. Gordon specializes in bone loss disorders of children and adolescents, and one of these disorders is idiopathic juvenile osteoporosis. Join me in welcoming Catherine Gordon MD, MSc, Associate Professor, pediatric endocrinologist and Director of the Bone Health Program from Children's Hospital in Boston, Massachusetts.

Catherine M. Gordon, MD, MSc: Dr. Gordon directs the Bone Health Program at Children's Hospital Boston and is an Associate Professor of Pediatrics at Harvard Medicine School. Her primary research interest is the effect of nutrition and malnutrition on bone in children and adolescents. She has published widely in the areas of skeletal losses in young women with anorexia nervosa, cystic fibrosis, inflammatory bowel disease, and vitamin D deficiency. Dr. Gordon has served as President of the Pediatric Bone and Mineral Working Group for the American Society for Bone and Mineral Research, directs the Pediatric Bone Density Course for the International Society for Clinical Densitometry and was elected to their Board of Directors, and was elected to the Society for Pediatric Research Council. Dr. Gordon has received independent funding through the Eunice Kennedy Shriver NICHD and Dept. of Defense to carry out research aimed to counter bone loss in adolescents with anorexia nervosa.

  • **I understand that you are involved in the Best Bones Forever campaign, sponsored by the Department of Health and Human Services as one of their panel experts. What does this group do to promote bone health and what age group are they targeting? **

_Best Bones ForeverTM_is a national bone health campaign designed to help girls, age 9-14, and their parents understand the importance of paying attention to diet, exercise, and other health habits to promote bone health. The teenage and adolescent years represent a critical period for the development of peak bone mass. Therefore, health habits initiated during childhood and adolescence can lead to a high bone density during adulthood, and potentially, the prevention of osteoporosis. The Campaign has designed informational materials including a website and other on-line references to provide health tips for girls and their parents about calcium, vitamin D, and other nutrients that are of importance for bone, as well as exercise.Examples of informational items include bone healthy grocery lists, list of foods containing bone healthy nutrients (e.g., rich in calcium and vitamin D), downloadable recipes, and activity lists. A highlight of the campaign is the encouragement of parents working with their daughters, to try to instill better health habits for both.

  • Doctor could you explain why it is so important for young girls and boys to start a program of calcium, vitamin D and weight bearing exercise early in life?

By age 18, the majority of an adolescent's peak bone mass has been achieved for life. The late childhood and adolescent years are therefore critical ones for bone development and accrual. There are modifiable factors in an adolescent's lifestyle, such as dietary intake and exercise that if optimized, can have a positive impact on the development of peak bone mass.

  • In addition to being a member of the Best Bones Forever campaign, you're also the Director of the Bone Health Program at Children's Hospital in Boston; could you explain your duties and field of interest at this facility within Harvard University?I direct the Bone Health Program and DXACenter** at Children's Hospital Boston** . I supervise the work of technologists who obtain bone density measurements, both for clinical care and research, by dual-energy x-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT). I also evaluate patients in my outpatient clinic who have been diagnosed with a low bone density (from various etiologies), have sustained frequent fractures, or have developed a disease or are undergoing treatments that are associated with bone loss. Our Program also has a research mission, and we try to organize symposia to bring together researchers from throughout the Harvard medical community with a common interest in bone health.
  • Dr. Gordon, I understand that one of the conditions you treat at Children's Hospital is idiopathic juvenile osteoporosis (IJO); could you explain this type of bone loss to our readers?

IJO is a "diagnosis of exclusion," meaning that it is the diagnosis given to a child when other etiologies of bone loss have been excluded. The diagnosis is made after a child has undergone extensive testing, including blood tests, x-rays, and DXA scans. These children can present at any age during childhood, but most commonly just prior to the initiation of puberty. Often these children have back pain and are later found on x-ray to have vertebral compression fractures and an accompanying low bone density. Others will present with leg or hip pain, a scoliosis from the weak skeleton, or a limp. Lastly, other patients will have no symptoms, but come to attention because "osteopenia" or washed out appearing bones are seen on a routine x-ray.

  • How is someone diagnosed with this disorder, is a DXA scan used or some other type of bone scanning device?

Most commonly, the diagnosis is made through DXA measurement of bone density, and a low bone mineral density (or BMD) is found.

  • What range of Z-score would a patient typically have if diagnosed with IJO?

The International Society for Clinical Densitometry has established that a DXA BMD Z-score below -2.0 SD (comparing the bone density to age- and gender-matched controls) is a significant low bone density. Children and teens with IJO almost universally have a BMD that is below this threshold.

  • What are the clinical features of this disease; do patients have loss of height, spinal deformity, and fractures; or some other physical symptoms?

Loss of height is not as common in children compared to adult with a low bone density. More commonly, children or adolescents fail to grow.

  • At what age do patients develop IJO, and is it generally just before puberty?

Children can present at any age, but most commonly, in the 1-2 years before the onset of puberty.

  • Do we know why IJO occurs just before puberty?

IJO is still a poorly understood disorder and deserves further study. These children may have a genetic predisposition to lose bone during late childhood. The bone loss appears to stem primarily from compromised function of the osteoblasts or bone-forming cells. An explanation for the timing of presentation, including the role of pubertal hormones is not clear. Interestingly, both boys and girls with IJO gain significant bone mass as they progress through puberty, suggesting that the arrest of osteoblast function is transient.

  • Do your patients usually have fragility fractures before they are diagnosed with IJO, or are there other physical criteria?

Most often, these children present with pain or an abnormal radiologic result (standard x-ray or DXA result).

  • Do both young girls and boys contract this disorder and how prevalent is it?

Yes, IJO occurs in both boys and girls. It has been classified formally as a rare disease.

  • What types of treatments are available for IJO, and can this disorder be resolved with non-drug therapy treatments?

Often these patients are monitored closely, optimizing calcium and vitamin D intake and make sure that the child is not vitamin D deficient (through a blood test). Cautious weight-bearing exercise is also prescribed, and often under the supervision of a physical therapist. Bisphosphonates are occasionally used when these patients present with a pathologic (atraumatic) fracture.

  • **Since you occasionally use bisphosphonates (Actonel ®, Boniva ®, Fosamax ® or Reclast ®), do you also consider anabolics, like Forteo ®, to treat this bone disorder? **

_Yes, we use consider use of bisphosphonates in patients who sustain pathologic fractures (fractures in the absence of trauma), but do not use Forteo due to the lack of safety testing in this young population. _

  • Would the dosing on bisphosphonates be different than those used for post-menopausal women?

Dosing per weight is followed in a child unlike set doses that are prescribed for adults.

  • Sincisphosphonates are used, do you limit the length of treatment?

Each case is individualized. Children with IJO typically need only 1-2 years of bisphosphonate therapy before gains in BMD are seen with the onset of puberty.

  • Do these patients with IJO that are treated with a bisphosphonate, have to worry about spontaneous femur fractures, bone and joint pain, gastrointestinal side effects or atrial fibrillation?

Before initiation of a bisphosphonate, a careful medical history is taken to make sure that a child has a normal swallowing mechanism and does not have gastroesophageal reflux or other gastrointestinal conditions that may be aggravated by an oral bisphosphonate. Signs of reflux are also carefully monitored for as these patients are followed on the medication. Bone pain is common after early initiation of a bisphosphonate, but then typically resolves completely over time. To date, spontaneous femur fractures and atrial fibrillation have not been documented in children or adolescent receiving bisphosphonate therapy.

  • Is there some preventative means that can be used for these patients to protect them from fractures; like bracing, padding or some other types of bone protection?

We typically do not use these strategies in children. We endorse cautious weight-bearing activities, as mentioned, often under the guidance of a physical therapist.

  • Do contact sports present a tremendous risk with IJO, or can someone with this lead a normal active life?

Yes, contact sports are generally avoided in patients with IJO until the bone density improves.

  • Could you give us an example of rehabilitation for these patients once they've had a fracture, and whether there is surgery involved?

In my practice, I have not had a patient with IJO need surgery after a fracture. Almost universally, I involve skilled physical therapists, who have experience with children to formulate a plan for rehabilitation.

  • Dr. Gordon, do you have any final thoughts on IJO that would add to our understanding of this disorder?

I would like to underscore the fact that more research is needed to understand IJO, including the genetics and role of pubertal hormones in this disorder. The optimal treatment for these patients also deserves further study.

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Thanks for helping to "get out the word" re: our national bone health campaign!

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Thanks Dr. Gordon for a wonderful informative interview, on IJO.