Search

Background While the inverse relationship between serum ionized calcium (Ca2+) and PTH is well-established, the relationship between 25(OH)D and PTH showed conflicting results. The study aimed to evaluate the relative contributions of age, sex, serum Ca2+, ionized magnesium (Mg2+), 25(OH)D and 1,25(OH)2D in regulating PTH secretion in healthy subjects. Methods This is a secondary analysis of an observational study performed from March 2014 to July 2015 carried out in 2259 blood donors (1652 men and 607 women, age range 18–68 years). Subjects with parathyroid disorders and taking drugs that affect mineral metabolism were excluded. Results Significant correlations [between Ca2+ and PTH (r = −0.223, p Discussion Under stable conditions 25(OH)D plays a significant role in regulating PTH secretion. Under conditions of relative vitamin D sufficiency, Ca2+ also plays an important role.

Introduction Previous papers investigating vitamin D status have often outlined the significant relationships between serum parathyroid hormone (PTH) and 25-hydroxyvitamin D (25OHD), but the influence of ionized calcium levels has not been concomitantly considered. Design Cross-sectional. Materials and methods In 1050 healthy men (547) and women (503), serum ionized calcium (iCa), creatinine (Cr), albumin, 25OHD, and PTH were measured. After conventional analysis, a regression tree was fitted on the data set. Results 25OHD and PTH values showed significant opposite seasonal changes. 25OHD levels negatively correlated with PTH, which in turn negatively correlated with iCa. A regression tree was fitted to the whole data set using PTH as the response variable and 25OHD and iCa as covariates. PTH concentration depended on that of iCa only in subjects with 25OHD levels > 16.35 ng/mL, while for 25OHD Conclusions Our results indicated that PTH levels were highly conditioned by those of 25OHD in subjects with 25OHD values lower than 16.35 ng/mL and by those of iCa only for higher 25OHD concentration.