- Prior other diseases: History of liver failure (AST or ALT >3 ULN), history of intestinal malabsorption or chronic diarrhea, corrected serum calcium >10.5 mg/dl, calcium x phosphorus product >70,treatment with more than 1000 IU of vitamin D per day; or current treatment with a vitamin D analogue or calcimimitec, taking antiepileptic medication, or other medications that could alter vitamin D metabolism(eg, phenytoin, phenobarbital, rifampin(17)