Study design
Vitamin D deficiency was defined as a circulating 25(OH)D levels of less than 20 ng/mL (50 nmol/L), insufficiency as 20–29 ng/mL, sufficiency as ≥30 ng/mL (75nmol/L) according to the Endocrine Society Clinical Practice Guideline [14]. Severe vitamin D deficiency is defined as 25(OH)D levels less than 10 ng/mL [22]. Hypervitaminosis D defined serum level of 25(OH)D >50 ng/mL (125 nmol/L) and toxicosis as >100 ng/mL (250 nml/L) [23, 24]. Subjects were evaluated into subgroups according to age, sex, the season for vitamin D levels. The data were classified according to age (18–29 years, 30–39 years, 40–49 years, 50–59 years, 60-69 years, 70–79 years, and ≥80 years). Season classifications were: winter (December, January, and February), spring (March, April, and May), summer (June, July, and August), and autumn (September, October, and November).