BGLAP and hyperthyroidism: Thus, bone resorption is favored leading to a negative calcium balance and bone loss.28,29 In addition, serum levels of bone turnover markers, such as ALP and osteocalcin, are elevated and could remain high for a few months after treatment of hyperthyroidism and normalization of serum thyroid hormones.30 In our case, concentrations of ALP remained high for several years due to undiagnosed central hyperthyroidism.