ABSTRACT

There is lack of studies on the relationship between parathyroid hormone and vitamin D levels for defining deficiency and insufficiency of vitamin D in adults living in Turkey. Therefore, we searched for threshold value of 25-hydroxyvitamin D concentration below which parathyroid hormone levels would significantly increase.

Between the dates of 01.03.2015 and 01.06.2015, the results of patients older than 18 years were scanned from the laboratory information system. Eight hundred three patients, whose simultaneously analyzed serum levels of calcium, inorganic phosphate, creatinine and intact parathyroid hormone were within the reference ranges and 25-hydroxyvitamin D was <50 ng/mL, were included in the study.

There was a significant difference in intact parathyroid hormone levels between subjects with 25-hydroxyvitamin D levels of 15-10 and those with 10-5 ng/mL (p=0.05). A significant increase in intact parathyroid hormone levels (p=0.01) was found to start with a 25-hydroxyvitamin D level below 22 ng/mL within the range of 30 to 10 ng/mL. Consequently, we determined the first 25-hydroxyvitamin D threshold in which intact parathyroid hormone levels significantly increase to be 22 ng/mL and the second threshold as 10 ng/mL.

Evaluation of parathyroid hormone which has a major role in the regulation of vitamin D should be done to define and diagnose vitamin D deficiency and insufficiency correctly.