The main reason of exclusion was the absence of serum PTH values (n = 368), followed by duplicate records (n = 192), children (n = 317), normal PTH (n = 103), hyperparathyroidism (n = 125), hypercalcemia (n = 191), transient hypoparathyroidism (n = 6), pseudohypoparathyroidism (n = 6), hypomagnesemia (n = 1), hungry bone syndrome (n = 3), and other causes (n = 2). Here, PTH is linked to pseudohypoparathyroidism type 1A.