Synopsis:
Vitamin D insufficiency in adolescents living at an intermediate altitude; and optimal serum 25(OH) vitamin D levels in relation to serum PTH levels was evaluated. In spring, vitamin D deficiency was detected in 17.7 % and vitamin D insufficiency was detected in 72 % of subjects. At the end of summer these rates were 1.6 % and 41.1 % respectively. Serum 25(OH)vitamin D levels at which plasma PTH concentrations begin to form a plateau is 22 ng/mL.