PTH and Hypercalciuria: To conclude, this study demonstrates that 40% of patients with a final diagnosis of PHPT are normocalcemic following a 48-hour calcium-restricted diet, with half of NHPT having apparently normal calcium homeostasis despite hypercalciuria (ie, normal fasting iCa with normal serum PTH concentration) while the other half meet the expected criteria defined by “a normal total and ionized serum calcium level without any other known etiology for a secondary elevation of parathyroid hormone (PTH)” (2, 3).