PTHLH and Hypercalcemia: With respect to the relationship between 1,25-dihydroxyvitamin D and PTHrP, a 2021 case report from Kim et al illustrated dual mechanisms of hypercalcemia (simultaneously elevated PTHrP and 1,25 dihydroxyvitamin D) and argued that a lack of response to bisphosphonate therapy with normalization of calcium following glucocorticoids effectively indicated that PTHrP was not the sole driver of the patient's hypercalcemia [9].