PTHLH and hypercalcemia disease: In patients with LOH, the hypercalcemia results from a variety of osteoclast activating factors, which are responsible for the significant increase in osteoclast absorption (Roodman, 2004), while HHM is caused by considerable flow of parathyroid hormone-related protein (PTHrP) derived from malignant cells (Guise et al., 1996).