Height, whole Body Surface Area, gender, working outdoors, and sunbathing in previous summer are important determinants of serum 25-hydroxyvitamin D levels

Objective: To investigate if serum 25-hydroxyvitamin D (25(OH)D) is related to the whole Body Surface Area (BSA), and to several other anthropometric and environmental factors.

Materials/methods: Serum 25(OH)D was determined in 489 apparently healthy subjects (346 women and 143 men, mean age 43.9 years) in April and May. From all subjects the following data were available: height, body weight, waist to hip ratio, BSA, BMI, environment of work (indoors vs. outdoors), habit of regularly sunbathing during previous summer(s), fear of sun, dwelling in city or village, and skin color.

Results: Approximately 43% of the participants had serum 25(OH)D levels between 10 and 20 ng/ml, 44% had values between 20.1 and 30 ng/ml, whereas about 5% had values below 10 ng/ml and only 9% had values above 30 ng/ml. There was a significant positive relationship between 25(OH)D, height and BSA, which was more pronounced for BSA in obese subjects even after adjustment for work outdoors and sunbathing during previous summer(s). Outdoor workers and sunbathers had higher 25(OH)D compared to indoor workers and non-sunbathers respectively. Men when compared to women had higher 25(OH)D regardless of BMI and this difference was apparently due to the fact that men were taller, had greater BSA, and worked more often outdoors.

Conclusions: Height, whole BSA, gender, working outdoors and sunbathing in previous summer(s) proved to be significant determinants of serum 25(OH)D. Vitamin D status is higher in taller individuals with greater BSA, and in men when compared to women.