Vitamin D deficiency: are we identifying it properly?
Subclinical deficiency of vitamin D or vitamin D deficiency is prevalent throughout the world, and there is great variability depending on the geographic region, genetic factors and lifestyle considerations.
Moreover, researchers now believe that serum 25-hydroxyvitamin D (25OHD) levels are the best indicator of vitamin D, although there are methodological issues that limit comparability between studies and how to establish deficiency cutoffs.
There are several criteria to establish the optimal level of 25OHD, which include the degree of maximal suppression of PTH, the intestinal absorption of mediated calcium 1,25(OH)2 vitamin D or reduction of fractures. Regarding the former, several studies have analyzed 25OHD concentration required for maximum suppression of PTH and offer variable results. This has led some researchers and scientific entities to recommend 25OHD levels above 20 ng/ml (Institute of Medicine, IOM) while others advise over 30 ng/ml (Endocrine Society, International Osteoporosis Foundation). The application variable for these recommendations has generated considerable confusion in clinical practice.