A recent Italian study is the first of its kind to see if giving vitamin D to young children reduces growing pains.
Morandi G, Maines E, Piona C, et al. Significant association among growing pains, vitamin D supplementation, and bone mineral status: results from a pilot cohort study. J Bone Miner Metab. 2014; epub ahead of print.
Growing pains, or recurrent lower limb pains, are the most common cause of musculoskeletal pain in children and affect up to 49.4% of children. The pain usually occurs in the late day or night and is diagnosed by exclusion of other disorders. It was first defined by the French physician Duchamp in 1823.
In 1960, Brenning et. al proposed growing pains were due to a “higher growth velocity rate.” However, the authors of this study noted that growing pains are most common in children before the growth spurt of puberty, there is no evidence that children experiencing growth pains are growing any faster than those without similar pain, and markers of bone cell activity and growth are normal in children with the pain.
Because children with growing pains are often vitamin D insufficient and deficient, the authors proposed the pain is due to less dense bones as a result of having a low vitamin D status. In this state abnormal pressure on sensory nerves of the bone can occur, causing pain.
Thirty-three children with growing pains were enrolled in the study. The mean age was 8.1 years old. Pain levels were assessed with a rating scale and bone density was assessed with ultrasound. Baseline vitamin D levels were measured and the children were divided into the following groups:
- Vitamin D sufficiency: at or greater than 30 ng/mL
- Vitamin D insufficiency: less than 30 ng/mL but greater than 20 ng/mL
- Vitamin D deficiency: less than 20 ng/mL
- Severe vitamin D deficiency: less than10 ng/mL
Children with 25(OH)D levels greater than30 ng/mL were not given any vitamin D supplementation. Children with vitamin D insufficiency were given 25,000 IU of oral vitamin D once per month for three months. Those who were vitamin D deficient received 100,000 IU of oral vitamin D once per month for three months, and those who were severely deficient received a vitamin D injection of 100,000 IU per month for three months. The children continued taking vitamin D supplements until the end of the 24-month study.
The researchers were interested in how these vitamin D doses affected the children’s vitamin D levels and if vitamin D supplementation reduced the perceived growing pain.
Thirty-one of the children had vitamin D levels below 30 ng/mL and three-quarters of the children had bone mineral density levels below the normal mean value of 0. After three months of treatment, the average 25(OH)D level increased from 15.7 ng/mL to 34.1 ng/mL and mean pain levels decreased significantly from an average level of 7.5 to 2.7. In eight children the pain disappeared completely. Bone mineral density improved, but the results were not statistically significant.
After 24 months of vitamin D therapy the increases in bone mineral density were statistically significant. Vitamin D levels remained elevated over baseline and pain levels remained decreased. One limitation of the study is the authors did not specify exactly how much vitamin D the children took for the remainder of the study after their first three doses.
There was no correlation between initial levels of pain and vitamin D status, but pain is subjective and difficult to accurately measure. Notably, significant reductions in pain were noted within individual participants after vitamin D therapy.
The authors attribute the decreases in pain observed to increased bone mineralization, which decreases the pressure on the nerves of bones. While the role of vitamin D in bone health is well established, this intriguing finding may very well describe a novel understanding for vitamin D in maintaining bone health.