Iron

Educational overview

Confirm deficiency and formulation. Oral overdose can be fatal in children, while IV products carry hypersensitivity and hypotension risks.

Iron is an essential mineral and the functional core of haemoglobin, myoglobin, and many enzymes involved in oxygen transport, energy production, and DNA synthesis. Dietary iron is absorbed in the duodenum under the control of the hormone hepcidin, and there is no physiological route for excreting excess, so the body regulates iron by limiting uptake. Iron deficiency is the most common nutritional deficiency worldwide and the leading cause of anaemia. Oral supplements contain ferrous salts (sulfate, gluconate, fumarate), polysaccharide-iron complexes, or heme iron, which differ in elemental iron content and gastrointestinal tolerability. Intravenous iron products such as iron dextran, iron sucrose, ferric carboxymaltose, ferumoxytol, and ferric derisomaltose are prescription drugs for deficiency that oral iron cannot correct.

The evidence base is large and mature. Randomized trials establish that oral iron corrects iron-deficiency anaemia, and absorption studies show that hepcidin rises after each dose, which is why less frequent schedules absorb comparably with fewer side effects. Intravenous iron trials show faster repletion in chronic kidney disease, heart failure, inflammatory bowel disease, and pregnancy, and the agents differ in their rates of hypersensitivity reactions. Toxicity is equally well documented: acute overdose causes corrosive gut injury, shock, and liver failure, and accidental ingestion of iron supplements was a leading cause of fatal poisoning in young children in the United States in the 1980s and 1990s, which prompted the mandatory warning label. Hereditary haemochromatosis makes ordinary supplement amounts harmful over years.

In the United States, oral iron is a dietary supplement, but FDA requires solid iron-containing supplements to carry a warning that accidental overdose is a leading cause of fatal poisoning in children under six. Intravenous iron products are FDA-approved prescription drugs: iron dextran (INFeD) carries a boxed warning for anaphylactic-type reactions, including fatalities, and its label calls for a test dose and resuscitation facilities, while the newer agents carry serious hypersensitivity warnings of their own. Intramuscular iron is now rarely used. No compounded injectable iron has approved status, and injectable iron sold outside pharmacy channels is unapproved. Other jurisdictions treat oral iron as a food supplement or pharmacy medicine and every intravenous iron product as a prescription-only medicine given under observation.

Oral iron is stable at room temperature in a closed container and, because of the paediatric poisoning history, is sold in child-resistant packaging. Intravenous products are stored per label and administered in clinical settings with observation for reactions. For a record, the salt and its elemental iron figure are the important numbers, since ferrous sulfate, gluconate, and fumarate tablets of similar weight contain very different amounts of iron. Timing relative to levothyroxine, quinolone and tetracycline antibiotics, calcium, and zinc is relevant because iron reduces their absorption or they reduce its, and dark stools and constipation are expected effects worth logging rather than alarming signs. Ferritin and transferrin saturation dated against the dose log show whether repletion is progressing.

Category

Mineral / hematologic

Routes represented

Oral

Storage context

Follow the product label; store in the original container away from excess heat and moisture.