A test used to help diagnose a type of pancreatic islet cell tumor called a gastrinoma. The patient receives a 3-hour infusion of a substance called calcium gluconate and the amount of gastrin in the blood is measured. An increase in the level of gastrin in the blood after the infusion may be a sign of a gastrinoma. ORA drug used to lessen the toxic effects of substances that block the action of folic acid, especially the anticancer drug methotrexate. Calcium levoleucovorin is used to treat some types of anemia and is also used with fluorouracil to treat colorectal cancer. It is also being studied in the treatment of other types of cancer and other conditions. Calcium levoleucovorin is a form of folic acid. It is a type of chemoprotective agent and a type of chemosensitizing agent. Also called citrovorum factor, leucovorin calcium, and Wellcovorin. OR An orally bioavailable aqueous solution containing the chloride salt of the radioisotope calcium-46 (46Ca) with phosphate-binding and radioisotopic activities. Upon administration of calcium-46 chloride aqueous solution, calcium-46 is preferentially taken up by osteoblasts, which generate mineralized osteoid containing calcium. Calcium-46 accumulation and turnover in bone can be measured with bone scintigraphy and urinary isotope excretion testing