Pediatric vitamin D deficiency in a southwestern luminous climate.

BACKGROUND: Few studies look at vitamin D levels in children living in sunny climates as it is assumed that they receive adequate vitamin D from sun exposure. In light of changing lifestyles of children and studies documenting vitamin D deficiency among children in extreme climates, a study to examine vitamin D levels in healthy children living in a luminous climate was conducted. METHODS: A retrospective chart review of vitamin D levels in healthy children with vague musculoskeletal pain (such as "growing pains") was done. Healthy children, specifically without musculoskeletal pain, were prospectively recruited as controls. RESULTS: Eighty-eight children, 42 children with "pain" and 46 controls were studied. No statistical difference in vitamin D levels was found between the "pain" group (mean vitamin D level 29.1 ng/mL) and the control group (mean vitamin D level 32.4 ng/mL, P<0.52). Overall, 14% of the entire group had levels <20 ng/mL, 49% had levels <30 ng/mL, and 15% had levels >40 ng/mL. CONCLUSIONS: A consensus has yet to be established as to what an "optimal" vitamin D level is for growing children to develop strong bones for a lifetime. This study demonstrated that 14% of children living in a sunny climate had vitamin D levels below 20 ng/mL, a level universally accepted as insufficient, and 49% were below 30 ng/mL, arguably a "desired" level. A sunny climate does not assure vitamin D sufficiency. Virtually all children should be supplemented, with laboratory follow-up for those at high risk for low bone density/those with insufficiency fractures.

The lateral distal femoral DEXA scan in children: a chronology of growing bone?

Dual energy x-ray absorptiometry (DEXA) is the current standard for measuring bone mineral density (BMD) in children. The International Society for Clinical Densitometry recommends scanning the total body and spine in children. However, in orthopedics, the total-body and spine DEXA scans are often rendered useless by the presence of metallic hardware and/or contractures. The lateral distal femoral DEXA scan was developed as a scan mode for children such as those with cerebral palsy who have contractures or metallic implants, which make it impossible to do total-body or spine scans. Unlike other DEXA scans, a single scan of the lateral distal femoral illustrates the density of the metaphyseal cancellous (newer) bone, the transitional, and the cortical (older) bone in 1 image. Because of this, we hypothesized that an individual lateral distal femoral scan could provide a map of bone health over time. The lateral distal femoral scans of 40 children whose bone growth was tainted by distant chemotherapy (chemotherapy group) were compared to the lateral distal femoral scans of 40 children whose bone environment had remained relatively stable over time (control group). The hypothesis was not confirmed by the data. The "Z-score difference," the difference between the Z-scores of the cancellous and cortical bone, for the chemotherapy group (0.16) and the control group (0.32) were not statistically different. While these results did not confirm the hypothesis, the lateral distal femoral scan remains a reproducible and useful DEXA scan in pediatric orthopedic clinical practice.