Reply to Whiteman et al.: In-Deed wise to get some sensible sun exposure

The Role of Vitamin D in Pediatric Orthopedics

Understanding the role of vitamin D is an important component of the proper care of the pediatric orthopedic patient. Vitamin D is an essential component of bone metabolism in the growth and development of the pediatric skeleton, which can be acutely affected by changes to the body's vitamin D, calcium, and phosphate levels, resulting in pathologic conditions such as rickets or fractures. This article reviews the main areas in which vitamin D relates to pediatric orthopedics and highlights some of the areas where future research is being directed.

Evaluation of vitamin D plasma levels after mild exposure to the sun with photoprotection

BACKGROUND

Most of the organism's vitamin D (VD) is obtained through the cutaneous synthesis after exposure to the sun's UVB radiation. Sunscreens are indicated for the prevention of actinic damage to the skin, however, there are few clinical trials assessing the synthesis of cutaneous VD in real-life situations of sun exposure with ordinary clothing and usual photoprotection.

OBJECTIVES

To evaluate the synthesis of VD with suberythemal sun exposure in healthy adults using topical photoprotection (SPF 30).

METHODS

Quasi-experimental study, conducted at Rio de Janeiro (Brazil), during winter, with 95 healthy adults who had 25-OH-VD checked twice, 24 hours apart, and were exposed to the sun (UVB=20 mJ/cm2), according to a randomized grouping: SC - use of SPF 30 on the face, neck and chest (n=64), NO - no sunscreens (n=10), CO - confined from sun exposure for 24h (n=21). The groups were matched according to the propensity score related to gender, age, phototype, body mass index, glycosylated hemoglobin and baseline levels of VD. The outcome evaluated was the variation (ΔVD) in serum level of 25-OH-VD (ng/ml) between the groups.

RESULTS

A statistically significant difference was identified between CO and SC groups [median (p25-p75)]: ΔVD =1.4 (-0.3-3.6) vs. 5.5 (4.8-6.6); p<0.01. There was no difference between SC and NO groups: 5.4 (3.1-6.1) vs. 4.1 (2.5-6.0); p=0.17.

STUDY LIMITATIONS

Laboratory analysis technique (chemiluminescence) with great variability, loss of food intake standardatization, unbalanced groups.

CONCLUSIONS

Suberythemal sun exposure with sunscreen (SPF 30) provides similar vitamin D serum variation than without photoprotection in healthy adults.