INCLUSION CRITERIA:  In order to be eligible to participate in this study, an individual must meet all of the following criteria:  Subjects known to have, suspected of having, or at risk of developing a disorder of bone and mineral metabolism. Age >= 6 months.  EXCLUSION CRITERIA:  An individual who meets any of the following criteria will be excluded from participation in this study:  Incarceration Patients with drug-related disturbances of mineral metabolism Patients with post-surgical hypoparathyroidism or vitamin D - deficiency associated hypocalcemia. Patients with conditions that in the opinion of the investigators can interfere with the study objectives