Hypercalcemia of malignancy?,”Hypercalcemia of malignancy may be due to osteolytic metastasis, increased tumor production of PTHrP, increased tumor production of 1,25-Vitamin D
or increased interleukin-6 levels. PTH levels are suppressed in patients with hypercalcemia of malignancy. Serum calcium levels are generally much higher (>13 mg/dL) in patients with hypercalcemia of malignancy than in those with primary hyperparathyroidism.”