Vitamin D in the diet undergoes changes in the liver and kidneys to several forms. Patients
suffering from disorders with Vitamin D resistance are unable to absorb calcium from food.
Patients diagnosed with these disorders will be evaluated and treated with high doses of
another form of Vitamin D (1,25-dihydroxyvitamin D3). Patients will be monitored and
observed throughout the study to avoid experiencing side effects from the medication.
Patients with extreme resistance to 1,25-dihydroxyvitamin D will be evaluated and treated
with high doses of 1,25-dihydroxyvitamin D3.
Plan: In previously untreated patients the study will be divided into a control and one or
more treatment periods. During the control period, parathyroid status will be assessed by
parameters nos. 1& 2 (below). In previously treated patients maintenance vitamin D will be
gradually replaced with 1,25(OH)2D3. This will be accomplished by withdrawal of vitamin D
and institution of 1,25(OH)2D3 when the serum calcium shows a downward trend.
1,25(OH)2D3 as 0.25 or 0.5 ug capsules (though IND 20,889) or as a solution of I microgram
per ml will be administered orally. In most cases, because of consideration of time and
expense, the cooperation of the patient's local physician will be enlisted. The following
will be monitored:
1. Serum calcium, phosphorus,alkaline phosphatase,creatinine at twice weekly intervals.
After a maintenance dose has been established, this will be decreased to a monthly, and
subsequently 3-6 monthly interval.
2. Urine calcium, phosphorus,creatinine and cAMP before therapy and, when appropriate,
The dose of 1,25(OH)2D3 will be 0.125 to 50.0 ug/day. Serum calcium will not be allowed to
rise above the normal range (2.0 -2.4 mM at NIH). Should hypercalcemia occur, appropriate
treatment will be initiated and the drug dosage will be decreased.
- INCLUSION CRITERIA:
Patients with hereditary resistance to calcitrol.