Fig. 2.

Levels of serum 250HD at which serum PTH plateaus and/or is maximally suppressed, as demonstrated by 59 studies reviewed by Sai et al. (4). Not included are eight studies in which serum PTH continually decreased with increasing serum 25OHD and three studies that found no relationship between serum 250HD and serum PTH. [Reproduced from A. Sai et al.: Relationship between vitamin D, parathyroid hormone, and bone health. J Clin Endocrinol Metab 96:E436–E446, 2011 (4), with permission. ©The Endocrine Society.]