In medicine, Iron overload Indicates accumulation of iron In the body from any cause. The most important causes are hereditary haemochromatosis, a genetic disorder. and transfusional Iron overload, which can result from repeated blood transfusion. Terminology Haemochromatosis or haemoslderosls Historically, the term haemochromatosis was initially used to refer to what is now more specifically called haemochromatosis type 1 . Currently, haemochromatosis Is mostly defined as iron overload with a hereditary/primary cause, or originating from a metabolic disorder.
However, the term is currently also used more broadly to refer o any form of Iron overload, thus requiring specification of the cause, for example, hereditary haemochromatosis. Hereditary haemochromatosis is an autosomal recessive disorder with estimated prevalence In the population of 1 In 200 among patients with European ancestry, with lower incidence in other ethnic groups. The gene responsible for hereditary haemochromatosis is located on chromosome 6; the majority of hereditary haemochromatosis patients have mutations in this HFE gene.
Hereditary haemochromatosis Is characterized by an accelerated rate of Intestinal iron absorption and progressive iron deposition in various tissues that typically egins to be expressed in the third to fifth decades of life, but may occur In children. The most common presentation is hepatic cirrhosis in combination with hypopituitarism, cardiomyopathy, diabetes, arthritis, or hyperpigmentation. Because of the severe sequelae of this disorder if left untreated, and recognizing that treatment is relatively simple, early diagnosis before symptoms or signs appear is Important.
In general, the term haemoslderosls Is used to Indicate the pathological effect of iron accumulation in any given organ, which mainly occurs in the form of haemoslderln. Sometimes, the simpler term siderosls Is used Instead. Other definitions distinguishing haemochromatosis or haemosiderosis that are occasionally used include: Haemosiderosis Is haemochromatosis caused by excessive blood transfusions, that is, haemosiderosis is a form of secondary haemochromatosis.
Haemoslderosls is haemoslderln deposition within cells, while haemochromatosis Is haemosiderin within cells and interstitium. Haemosiderosis is iron overload that does not cause tissue damage, while haemochromatosis does. Haemosiderosis Is arbitrarily differentiated from haemochromatosis by the reversible nature of the iron accumulation In the reticuloendothelial system. Clinical presentation Organs commonly affected by haemochromatosis are the liver, heart, and endocrine glands.
Haemochromatosis may present with the following clinical syndromes: Cirrhosis of the liver Diabetes due to pancreatic islet cell failure Cardiomyopathy Arthritis Testicular failure Tanning of the skin Joint pain and bone pain 1 OF3 causes The causes can be distinguished between primary cases and less frequent secondary cases . People of Celtic, British, and Scandinavian origin have a particularly high incidence of whom about 10% are carriers of the gene and 1% sufferers from the condition.
Primary haemochromatosis The fact that most cases of haemochromatosis were inherited was well known for most of the 20th century, though they were incorrectly assumed to depend on a single gene. The overwhelming majority actually depend on mutations of the HFE gene discovered in 1996, but since then others have been discovered and sometimes are grouped together as “non-classical hereditary haemochromatosis“, “non-HFE related hereditary haemochromatosis”, or “non-HFE haemochromatosis”. Most types of hereditary haemochromatosis have autosomal recessive inheritance, while type 4 has autosomal dominant inheritance.
Secondary haemochromatosis Severe chronic haemolysis of any cause, including intravascular haemolysis and ineffective erythropoiesis Multiple frequent blood transfusions, which are usually needed either by individuals with hereditary anaemias or by older patients with severe acquired anaemias such as in myelodysplastic syndromes Excess parenteral iron supplements, such as what can acutely happen in iron poisoning Excess dietary iron Some disorders do not normally cause haemochromatosis on their own, but may do so in the presence of other predisposing factors.
These include cirrhosis, teatohepatitis of any cause, porphyria cutanea tarda, prolonged haemodialysis, and post-portacaval shunting. Diagnosis There are several methods available for diagnosing and monitoring iron loading including: Serum ferritin Liver biopsy MRI Serum ferritin is a low-cost, readily available, and minimally invasive method for assessing body iron stores.
However, the major problem with using it as an indicator of iron overload is that it can be elevated in a range of other medical conditions unrelated to iron levels including infection, inflammation, fever, liver disease, renal disease, and cancer. Also, total iron binding capacity may be low, but can also be normal. The standard of practice in diagnosis of haemochromatosis was recently reviewed by Pietrangelo. has been extensively validated. More than 11,000 FerriScans have now been conducted in over 120 medical centres across 25 countries.
FerriScan is now specifically recommended as a method to measure liver iron concentrations in clinical practice guidelines for thalassaemias, sickle cell disease myelodysplastic syndrome and hereditary haemochromatosis. Family members of those diagnosed with primary haemochromatosis may be advised to be screened genetically to etermine if they are a carrier or if they could develop the disease. This can allow preventative measures to be taken. Prognosis A third of those untreated develop hepatocellular carcinoma.