The reported range of patients with hypercalcemia whose PTH levels are obtained is 23.4% to 33.0%.13,15,18,19 Approximately 43% of those with hypercalcemia have PHP.15 However, the condition is diagnosed in just 1.3% to 8.0% of patients.15,18,19 The findings of this cohort study are consistent with historical data, noting a workup including PTH for approximately 2 of 5 patients. This evidence concerns the gene PTH and hypercalcemia disease.