In 2021, Song et al., in a systematic review and meta-analysis of 11 studies, showed that VD supplementation in patients with PHPT and VD deficiency (25-OH-D < 20 ng/mL) significantly reduces PTH and alkaline phosphatase levels without causing hypercalcemia and hypercalciuria (44). The gene discussed is PTH; the disease is hypercalcemia disease.