FERROUS CITRATE FE 59
Clinical safety rating: caution
Comprehensive clinical and safety monograph for FERROUS CITRATE FE 59 (FERROUS CITRATE FE 59).
Ferrous citrate Fe 59 is a radioactive isotope of iron used for diagnostic purposes. It is incorporated into hemoglobin in red blood cells, allowing visualization of erythropoiesis and imaging of the reticuloendothelial system.
| Metabolism | Iron is incorporated into hemoglobin; catabolism of heme releases iron, which is recycled. Fe 59 decays by beta and gamma emission. |
| Excretion | Fe-59 is primarily excreted via feces (80-90%) as unabsorbed iron, with minor renal excretion (<5%) and negligible biliary elimination. Absorbed iron is incorporated into hemoglobin and red blood cells, with loss via desquamation (~1 mg/day) not reflected in excretion fractions. |
| Half-life | Terminal elimination half-life of Fe-59 from plasma is approximately 1.5-2 hours for free iron, but for total body iron, it is about 5-6 hours initially, followed by a slow phase of 6-10 days due to redistribution to storage sites. Clinically, the long half-life allows imaging of erythropoiesis over days. |
| Protein binding | Transferrin binds ~30-40% of plasma Fe-59; ferritin and hemosiderin bind storage iron. Protein binding is primarily to transferrin with high affinity (Kd ~ 10^-23 M), and free iron is negligible (<1%). |
| Volume of Distribution | Volume of distribution is approximately 0.3-0.4 L/kg for plasma iron, but larger (0.6-1.0 L/kg) for total body iron due to tissue binding. The low Vd reflects tight retention in plasma and bone marrow. |
| Bioavailability | Oral bioavailability of ferrous citrate Fe-59 is around 10-20% in healthy individuals, but varies with iron stores (increased to 20-30% in deficiency). Intravenous administration yields 100% bioavailability. |
| Onset of Action | Intravenous: Distribution to bone marrow occurs within 30-60 minutes; incorporation into RBCs visible within 24 hours. Oral: Absorption begins within 1-2 hours, but clinical effect (e.g., hemoglobin increase) requires days to weeks. |
| Duration of Action | The biological effect (iron incorporation) lasts for the lifespan of the RBCs (120 days). Radiotracer Fe-59 is detectable for up to 14 days after administration as it is recycled in erythropoiesis. |
Ferrous citrate Fe 59 is a radioactive diagnostic tracer, not a therapeutic iron supplement. Typical adult dose: 2-10 µCi (0.074-0.37 MBq) intravenously as a single dose for iron absorption or red cell utilization studies.
| Dosage form | INJECTABLE |
| Renal impairment | No specific dose adjustment required; ferrous citrate Fe 59 is rapidly cleared by the reticuloendothelial system and not significantly renally excreted. Use with caution in severe renal impairment due to potential accumulation of radioactive decay products. |
| Liver impairment | No specific Child-Pugh based dose modifications established. Use with caution in severe hepatic impairment as liver may be primary site of iron uptake. |
| Pediatric use | Weight-based dosing: 1-5 µCi (0.037-0.185 MBq) intravenously, adjusted for body weight and study protocol. Maximum dose not to exceed 10 µCi. Use only when diagnostic benefit outweighs radiation risk. |
| Geriatric use | No specific dose adjustment; same adult dosing applies. Consider age-related decline in iron absorption and metabolism. Use lowest effective dose to minimize radiation exposure. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for FERROUS CITRATE FE 59 (FERROUS CITRATE FE 59).
| Breastfeeding | Excreted in breast milk; M/P ratio not established; discontinue breastfeeding during therapy to avoid infant radiation exposure. |
| Teratogenic Risk | No teratogenic risk; radioactive iron crosses placenta minimally; first trimester: theoretical risk from radiation; second/third trimester: risk of fetal thyroid accumulation of radioisotope. |
| Fetal Monitoring |
■ FDA Black Box Warning
None
| Serious Effects |
["Known hypersensitivity to ferrous citrate or any component","Pregnancy (unless benefit outweighs risk)"]
| Precautions | ["Radiation exposure: use lowest dose necessary","Pregnancy and lactation: avoid if possible","Hypersensitivity reactions possible"] |
| Food/Dietary | No specific food interactions. However, iron-rich meals may affect tracer distribution in GI bleeding studies; follow nil per os (NPO) orders if specified. |
| Clinical Pearls |
Loading safety data…
| Monitor CBC, serum ferritin, iron studies; fetal radiation exposure monitoring via dosimetry. |
| Fertility Effects | No known adverse effects on fertility. |
| FERROUS CITRATE FE 59 is a radioactive isotope used in ferrokinetic studies, not for oral iron replacement. Key tips: Avoid in pregnancy; ensure proper shielding; monitor for extravasation during IV administration; use in GI bleeding localization with caution due to rapid clearance. |
| Patient Advice | This medication is a radioactive tracer, not a vitamin or iron supplement. · You will receive a small dose of radiation; risks are minimal compared to diagnostic benefit. · Drink plenty of fluids after administration to help eliminate the tracer from your body. · Avoid close contact with pregnant women and young children for 24 hours after the test. · Inform your doctor if you are pregnant or breastfeeding. |