Clinical pharmacokinetics of iron preparations

The principle of iron conservation is the basis of iron metabolism; the normal basal loss of iron from the body is about 1 mg daily in a 70 kg man and 0.8 mg in a 55 kg woman. Iron is lost mainly by the menstrual and gastrointestinal routes. The total iron requirement during pregnancy is 800 mg; in the last month the requirement may amount to 7 to 8 mg/day. Supplementary iron is recommended for many menstruating women, and during the latter part of pregnancy. Correct fetal iron metabolism is ensured by proper maternal iron status, although there are contradictory opinions and findings about the relationship between maternal and fetal iron metabolism. Preterm infants fed on breast milk have a negative iron balance, and require an iron intake of about 0.6 mg/kg/day, and 3.4 mg/1 g haemoglobin, to compensate for intestinal and venesection iron losses, respectively. The absorption of supplementary iron by the preterm infant is a linear function of intake. Preterm infants do not require iron supplements when given repeated blood transfusions. During lactation the total iron losses of the mother are 1 mg/day, and thus no supplementary iron is needed if the iron metabolism has been in balance during the pregnancy. Serum ferritin concentration decreases continuously when iron stores in the body are reduced, and totally empty iron stores are the only known reasons for low serum ferritin concentration. Despite depleted iron stores, serum ferritin concentration can be normal or higher than normal in protein-energy malnutrition, up to 3 months after major surgery, in acute liver damage, in some patients with prolonged hyperglycaemia due to diabetes mellitus, in acute lobar pneumonia, active pulmonary tuberculosis and rheumatoid arthritis on gold therapy, in sepsis secondary to marrow hypoplasia induced by chemotherapy, in heavy drinkers and for a few days after myocardial infarction. In haemochromatosis, iron is deposited in liver (producing fibrosis), pancreas, endocrine glands and heart. The rise in the level of iron in the body is due to increased absorption and/or increased intake. This pathology may occur in transfusions, in alcoholism (especially when alcoholic beverages are contaminated with iron and the diet is low-protein), in several liver diseases, in congenital transferrin deficiency and in idiopathic disease. Patients susceptible to haemochromatosis should receive a low-iron diet. Serum ferritin determination may be helpful in early identification of susceptible members of a family with idiopathic familial haemochromatosis, but transferrin saturation is not a good indicator of either iron depletion or iron overload.(ABSTRACT TRUNCATED AT 400 WORDS)