The absorption, distribution and utilization of intramuscularly administered iron-dextran: a radio-isotope study

Summary. The rate and completeness of absorption of iron from the injection site were studied after intramuscular administration of 59Fe-labelled iron-dextran and the pattern of radio-iron distribution and utilization followed in normal subjects and patients with iron-deficiency anaemia. In both normal and anaemic subjects the major part of iron absorption took place within 72 hours of injection; absorption continued at a slower rate for 28 days but little further iron clearance occurred thereafter. Rate and completeness of absorption were not related to the presence or absence of iron deficiency or to the haemoglobin level. In both normal and anaemic subjects there was marked individual variation in iron clearance. Active exercise was not found to lead to increased iron absorption but both rate and completeness of iron clearance were shown to be influenced by the site of injection. A study was made of iron clearance after multiple injections of iron-dextran into the same site. Serial surface scintillation counting was carried out in both normal and anaemic subjects; in smaller numbers of subjects, serial estimations of serum-iron levels were made and percentage incorporation of radio-iron into haemoglobin measured. There was no evidence of significant excretion of radio-iron in urine and faeces, and no toxic manifestations were observed.