In a recent study, there were biochemical changes (low Ca++, low PO4, high PTH, and high ALP) when 25OHD was below 10 ng/mL, however, there was no biochemical evidence when the levels were between 20–30 mg/mL to justify labeling patients with vitamin D insufficiency or to justify vitamin D supplementation in this category [16]. Here, PTH is linked to vitamin D deficiency.