Iron-59
Iron is a necessary constituent of red blood cells, so its radioactive form, ⁵⁹Fe, has been used frequently in measurement of the rate of formation of red cells, the lifetime of red cells, and red cell volumes. The labeling is more difficult than labeling with chromium for the same purposes, so this procedure no longer has the importance it once had.
On the other hand, direct measurement of absorption of iron by the digestive tract can be accomplished only by using ⁵⁹Fe. In achlorhydria the gastric juice in the stomach is deficient in hydrochloric acid, and this condition has been shown to lower the iron absorption. A normal diet contains much more iron than the body needs, but in special cases, sometimes called “tired blood” in advertising for medicines, iron compounds are prescribed for the patient. If ⁵⁹Fe is included, its appearance in the blood stream can be monitored and the effectiveness of the medication noted.
This multiple-port scintillation counter is used for iron-kinetic studies. The tracer dose of iron-59 is administered into the arm vein and then the activities in the bone marrow, liver, and spleen are recorded simultaneously with counters positioned over these areas, and show distribution of iron-59 as a function of time. When the data are analyzed in conjunction with iron-59 content in blood, information can be obtained about sites of red blood cell production and destruction.