An interesting aspect that has been observed in few studies is that the alteration of the systemic mineral homeostasis following HSCT, also powered by post-transplant chronic glucocorticoid intake, affects the entire phosphate-calcium-PTH system by altering PTH secretion and causing the onset of secondary hyperparathyroidism, which, if not rebalanced, can lead to the development of chronic tertiary hyperparathyroidism. Here, PTH is linked to secondary hyperparathyroidism.