Assessment of the effect of phytic acid on the labeling of blood cells and plasma proteins with Technetium-99m

Blood elements labeled with technetium-99m (99m Tc) have been used in various procedures in nuclear medicine. We have investigated if phytic acid (PHY) could alter the labeling of blood elements with 99m Tc. Blood was incubated with different concentrations of PHY. Stannous chloride and 99mTc, as sodium pertechnetate, were added. Blood was centrifuged and plasma (P) and blood cell (BC) were isolated. Samples of P and BC were also precipitated with trichloroacetic acid and centrifuged, and insoluble (IF) and soluble (SF) fractions were separated. The percentages of radioactivity (%ATI) in BC, IF-P and IF-BC were calculated. The %ATI decreased significantly (p < 0.05) in BC (95.08 ±1.94 to 80.68 ± 3.35), in IF-P (74.42 ±4.50 to 39.94± 5.51) and in IF-BC (89.91± 3.91 to 79.54 ± 5.42) in presence of PHY. These results suggest that the chelating property of PHY can modify the labeling of the BC, although other effects of PHY could be responsible. As PHY is found in many food and it could alter the labeling of blood elements with 99m Tc with possible undesirable effects, it is relevant to verify the necessity to repeat the examination and to evaluate the increase of the radiation dose to the patient. (author)