PTH and chronic kidney disease: Rigorous selection was performed, following not only the traditionally required criteria [normocalcemia (in this study, total and ionized calcium); vitamin D sufficiency (defined as concentrations > 30 ng/dL); absence of chronic kidney disease, and no use of interfering drugs (2)], but also excluding other factors that can alter PTH in apparently healthy individuals (e.g., hypercalciuria, conditions of malabsorption, hyperphosphatemia, hypomagnesemia), which were not considered in previous studies (2,18,19).