Trace Element: Iron (Fe) (SAAS)
Biochemistry Overview / Directory
Purpose of the test
Iron may be considered a trace element if the large amounts present in haemoglobin are discounted. The recommended daily intake is 10-15 mg per day, of which only 1-2 mg is absorbed. The main transport protein for iron is transferrin, which is synthesised in the liver at a rate inversely proportional to body stores. Ferritin is an iron storage protein found in most cells of the body, particularly the liver, and provides a readily available reserve. Haemosiderin is an insoluble aggregate protein also found primarily in the liver during excessive storage and from which iron is less readily available.
Iron deficiency is one of the most prevalent disorders, even in developed countries. It may either be due to inadequate dietary intake or chronic blood loss. Acute iron toxicity from overdosage of inorganic iron tablets is the commonest acute poisoning in children. Chronic iron overload may arise from genetic haemochromatosis in which there is excessive iron absorption or secondary to repeated transfusions (transfusion siderosis in sickle cell disease or thalassaemia), or to alcoholic liver disease. Genetic haemochromatosis is due to mutations in the HFE gene (C282Y and H63D) and is primarily found in Caucasians.
Neonatal haemochromatosis is a rare, but particualrly severe cause of iron overload and is unrelated to the adult form. Liver transplantation within the first few weeks of life is required for survival.
A raised transferrin saturation (> 65%) is strongly suggestive of haemochromatosis. Until recently, diagnosis was usually confirmed by hepatic iron measurements, but today molecular techniques for identification of the above mutations is more common and less invasive. Treatment of transfusion siderosis is with the iron chelator desferrioxamine. Measurement of urinary iron excretion during chelation therapy can help optimise the dosage.
Reference Range
Transferrin saturation 15-50%.
Urine iron < 1 µmol/L.
Liver iron < 1500 µg/g dry wt. Hepatic iron index (iron/age) above 2.0 suggests haemochromatosis.
Sample Requirements
Serum (1 mL).
Urine (20 mL + urine volume).
A protocol for collection of liver biopsies for hepatic iron is available on request.
HFE genotype – EDTA sample (5 mL).
Storage and Transport
Stable at 4°C for up to two days. Send by overnight first class post.
PDF Request Form
Download Trace Element: Iron (Fe) (SAAS) Request Form
Turnaround Time
Urine/tissue iron 1-2 weeks. HFE genotype 3-4 weeks.
Price
Prices available on application - please contact adrianturner1@nhs.net. Discounts could be available for significant workloads.
Contacts
Dr Kishor Raja
T: 020 3299 4127
References
Raja KB, Jafri SE, Peters TJ, Simpson RJ. (2006) Iron and cadmium uptake by duodenum of hypotransferrinaemic mice. Biometals 19: 547-553
Laftah AH, Raja KB, Latunde-Dada GO, Vergi T, McKie AT, Simpson RJ, Peters TJ (2004) Effect of altered iron metabolism on markers of haem biosynthesis and on intestinal iron absorption in mice. Ann Hematol 84, 177-182
Laftah AH, Raja KB, Beaumont N, Simpson RJ, Deacon A, Solanki N, Srai SKS, Peters TJ (2004) The Effects of Inhibition of Haem Biosynthesis by griseofulvin on Intestinal Iron Absorption. Basic & Clinical Pharmacology & Toxicology, 94: 161-168
Laftah AH, Raja KB, Simpson RJ, Peters TJ (2003) Effect of Tin-mesoporphyrin, an inhibitor of haem catabolism, on intestinal iron absorption. British Journal of Haematology 122: 298-304
Cremonesi P, Acebron A, Raja KB, Simpson RJ (2002) Iron absorption: biochemical and molecular insights into the importance of iron species for intestinal uptake. Pharmacol Toxicol 91: 97-102
McKie AT, Barrow D, Latunde-Dada GO, Rolfs A, Sager G, Mudaly E, Mudaly M, Richardson, Barlow D, Bomford A, Peters TJ, Raja KB, Shirali S, Hediger MA, Farzaneh F, Simpson RJ (2001) An iron-regulated ferric reductrase associated with the absorption of dietary iron. Science 291: 1755-9
Raja KB, Jafri SE, Dickson SE, Acebron A, Cremonesi P, Fossati G, Simpson RJ (2000) Involvement of iron (ferric) reduction in the iron absorption mechanism of a trivalent iron-protein complex (Iron protein succinylate). Pharm Toxicol 87: 108-15
