BOSTON — The high prevalence of vitamin D deficiency found in a cohort of healthy children in a sunny Southwestern climate has prompted a call by the study's investigators for generalized routine screening of vitamin D levels among all children.
In a study designed to assess vitamin D levels in children living in a region with year-round sunshine and to compare vitamin D levels in children with vague musculoskeletal pain with those of children without pain, Dr. Elizabeth A. Szalay and her colleagues at the University of New Mexico Hospital in Albuquerque retrospectively studied the serum 25-hydroxyvitamin D (25[OH]D) levels of 77 healthy children who were seen for musculoskeletal pain but who lacked a concrete diagnosis to explain their pain (pain group). They also prospectively obtained serum 25(OH)D levels from 35 healthy children without pain.
The study included healthy children aged 2-16 years who were freely ambulatory and could play outside as they chose. It excluded children with any endocrinopathy and those taking medications that affect vitamin D metabolism, such as steroids or bisphosphonates, Dr. Szalay said in a poster presented at the annual meeting of the Pediatric Orthopaedic Society of North America.
The study population (mean age, 9 years) included 66 girls and 46 boys, and was primarily Hispanic (59) and white (37). The average 25-hydroxyvitamin D levels for the pain and control groups were not statistically different, at 28 ng/mL and 31 ng/mL, Dr. Szalay reported, nor did the vitamin D levels vary by month of the year.
Based on the collective data, the mean 25(OH)D level was 29 ng/mL. "While there is no consensus on optimal serum vitamin D levels in children, optimal calcium absorption is seen between 40 and 100 ng/mL," Dr. Szalay said. "Vitamin D deficiency is defined by most experts as a [25-hydroxyvitamin D] level less than 20 ng/mL."
Only 13% of the children had vitamin D levels in the optimal range, while 33% had levels from 30 to 39 ng/mL, 35% had levels from 20 to 29 ng/mL, 16% had levels from 10 to 19 ng/mL, and 3% had levels less than 10 ng/mL—the level at which rachitic changes may occur.
"This is an alarming trend, especially because the location—with its Southern latitude—had been thought to be ideal for adequate vitamin D levels," said Dr. Szalay. Despite the abundant sun exposure and lack of chronic illness, "the percentage of children with suboptimal vitamin D levels was significantly greater than that demonstrated among healthy teens studied in the 2002 Third National Health and Nutrition Examination Survey."
The findings seem to suggest that modern lifestyles, even among children living in sun-rich regions, may be taking an ever greater toll on pediatric vitamin D levels and indirectly on pediatric bone health, said Dr. Szalay. "Increasing childhood obesity, declining dairy intake, increased time using computers and video games, decreased outdoor activity, and increased sunscreen usage may be contributing factors impairing availability to vitamin D, which is essential for normal calcium metabolism and bone mineralization."
Dr. Szalay reported having no financial conflicts with respect to this presentation.