Although vitamin D repletion is typically linked to PTH suppression, as supported by previous studies including the recent systematic review and meta-analysis by Khodadadiyan et al.,11) this case shows that, under certain physiological conditions such as pre-existing low bone mineral density, active bone turnover, and insufficient calcium reserves, vitamin D supplementation can instead enhance skeletal calcium uptake and stimulate an increase in PTH levels, leading to secondary hyperparathyroidism. This evidence concerns the gene PTH and secondary hyperparathyroidism.