Patients with confirmed or suspected states with resistance to vitamin D or parathyroid
hormone (PTH) will be admitted for diagnosis, treatment review with suggestions for
modifications to the current or new treatment and for inclusion in other protocols. These
states include hypocalcemia, rickets, osteomalacia, pseudohypoparathyroidism. Resistance to a
factor is manifested by deficient bioeffect despite high levels of the factor in blood.
Patients will be tested with multiple indices of mineral metabolism to establish the
diagnosis and examine the spectrum of the underlying disorder. The principal therapies will
be combinations of calcium, phosphate, and a vitamin D analog. Selected patients will have
localization and surgery to remove a tumor that causes renal wasting of phosphate. Patients
will also be considered for entry into other research protocols.