,41 In support of our observation, an increasing number of clinical studies have identified cortical porosity as a hallmark of hyperparathyroid bone disease.6, 7, 8 As a plausible mechanism for these observations, a recent experimental study has shown that elevated PTH induces osteocytic osteolysis and osteocytic cell death in cortical bone, resulting in cortical porosity.42 The gene discussed is PTH; the disease is osteitis fibrosa.