Determination of 18O/16O ratio in inorganic phosphate as an oncogenic marker and indicator for disturbances in phosphate metabolism.

Natural stable isotope fractionation is a potential tool in investigation of metabolic process, since rigid mass balance considerations rule the changes in the isotopic ratio. As the natural changes in 13C/12C ratio of total CO2 between blood and urine served for studying renal bicarbonate reabsorption, studying changes in 18O/16O ratio of phosphate are suggested to investigate deranged phosphate metabolism. The 18O/16O ratio in serum phosphate is constant, determined by the ratio in the environmental drinking water. Therefore, measurements of this ratio in normal individuals, after modifications in phosphate metabolism and in diseases with high alkaline phosphatase activity are proposed. The main purpose of the proposed study is to assess whether measurements of 18O/16O ratio can detect malignant metastases in bones due to deranged phosphate metabolism. An assumption that these determinations might precede other tests for detecting bone metastases and can serve as an oncogenic marker is made.