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PostPosted: 29 Sep 2019 00:30 
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OVERVIEW OF TRACE ELEMENTS
• Minerals are inorganic substances needed in small amounts for a various functions.
• Some minerals such as calcium, magnesium, phosphorus, sodium, potassium and chloride are necessary in larger amounts for normal body function
• Others such as iron, zinc, copper, iodine, selenium and fluoride are required in very minute amounts and are referred to as trace elements or minerals. Nevertheless, trace minerals are no less important and deficiency of trace elements can lead to disease and have to be corrected
• The body requires different amounts of each mineral; people have different requirements, according to their age, sex, physiological state (e.g. pregnancy) and sometimes their state of health.

IRON INTRODUCTION
• Iron is an essential element for most living organisms since it plays a key role in several cellular functions including oxygen transport, electron transport and deoxyribonucleic acid (DNA) synthesis
• However, as iron can form free radicals, which are toxic chemicals, levels of iron in body tissues must be tightly regulated since excess iron levels can damage and cause tissue injury
• Disorders of iron metabolism are very common and produce wide ranging clinical manifestations ranging from anemia due to iron deficiency , diseases due to excess iron as well as neurodegenerative diseases.

IRON METABOLISM
• The fraction of ingested iron absorbed is quite low ranging from 5% to 35% depending on a person's condition and type of iron.
• Dietary iron occurs in two forms, namely heme and non-heme. Heme iron namely hemoglobin and myoglobin are obtained from animal sources, whereas non-heme iron is obtained from cereals, pulses, legumes, fruits, and vegetables. Heme iron has better bioavailability (15%-35%) and dietary factors have little effect on its absorption, whereas non-heme iron bioavailability is much lesser (2%-20%) and influenced by the presence of other food components. However, the quantity of non-heme iron found in diet is more than heme-iron
• Iron absorption occurs mainly in the duodenum and upper jejunum and transported across the duodenal mucosa into the blood. In the blood, it binds to transferrin (iron transporting protein) which transports iron to the cells or the bone marrow for erythropoiesis [producing red blood cells (RBCs)]
• There is a feedback mechanism that increases iron absorption in person who are iron deficient. In contrast, in persons with iron overload due to various causes, iron absorption is inhibited via hepcidin.
• Iron homeostasis in mammals is mainly controlled at the level of intestinal absorption, and there is no pathway for iron excretion.

IRON BIOCHEMICAL FUNCTIONS
• Iron is necessary for normal erythropoiesis
• Almost two-thirds of the body iron occurs in hemoglobin present in circulating erythrocytes, and 15% is bound to myoglobin in muscle tissue and present in enzymes that perform various functions
• Heme-iron compounds such as hemoglobin or myoglobin are involved in oxygen transport
• Heme-iron is a component of enzymes containing iron which are involved in electron transport,
• Non-heme compounds such as flavin-iron enzymes for various cellular activities, transferrin, and ferritin (storage form of iron).

IRON STORAGE
• About 25% of iron is in the form of iron stores in the form of ferritin and hemosiderin. Ferritin levels together with that of hemosiderin reflects the body iron stores.
• Stored iron is in an insoluble form and present mainly in the bone marrow, liver and spleen. Hemosiderin iron is less readily released iron for body needs.
• Under physiological conditions therefore, serum ferritin levels correspond well with total body iron stores. Thus, serum ferritin is the most often laboratory test to measure iron stores.

IRON RECOMMENDED DAILY REQUIREMENT (RDA)

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IRON EXCRETION
• Iron is highly conserved and not readily lost from the body, although there are some obligatory loss of iron from the body during exfoliation of cells from epithelial surfaces. However, these losses are minimal (≈1 mg/day).
• Significant iron losses through menstrual and other bleeding sources can be serious and lead to iron deficiency. Excessive menstrual blood loss is the most common reason of iron deficiency in women.

IRON DEFICIENCY
Iron deficiency is a common condition and groups at high risk of developing iron deficiency include situations where iron requirement is high, poor diet or there is iron loss due to bleeding
• Growing children
• Adolescents
• Menstruating women
• Pregnancy

Other causes include
• Gastrointestinal or genitourinary abnormalities resulting in blood loss
• Hookworm infection
• Improper dietary intake
• Alcoholism
• Frequent pregnancies

SYMPTOMS OF IRON DEFICIENCY ANEMIA
When iron stores are depleted and there is little or no iron for erythropoiesis, hemoglobin synthesis in erythrocyte precursors become impaired and hematologic signs of iron deficiency anemia appear

• Weakness & fatigue
• Pale skin and eyes
• Shortness of breath and chest pain
• Palpitations
• Headache and light-headedness
• Sore tongue
• Spoon shaped and brittle nails
• Craving for foods such as dirt and starch (pica)
• Loss of appetite

DIAGNOSIS OF IRON DEFICIENCY ANEMIA
Full blood count
May reveal reduced hemoglobin levels and reduced mean corpuscular volume (MCV)

Circulating Iron Levels
The plasma or serum pool of iron is the fraction of iron in the body is that which circulates in the blood bound primarily to transferrin. Estimation of serum iron can be done by the following tests

1) Estimating the total serum iron content per unit volume in μg/dL
2) Estimating the total number of binding sites for iron atoms on transferrin, referred to as total iron-binding capacity in μg/dL2; and
3) Measuring the percentage of binding sites on all transferrin molecules that are occupied by iron atoms referred to as called the percentage transferrin saturation

Estimating Storage Iron Levels
Serum ferritin is a good indicator of body iron stores. If the serum ferritin level is ≥15 μg/L it indicates presence of iron stores; when the concentration is low (<12 μg/L for <5 years of age and <15 μg/L for >5 years of age) storage iron is depleted

Finding The Cause of Iron deficiency
• Upper and lower GI endoscopy
• Menstrual history & Gynecological check-up
• Urology review to rule out genitourinary pathology
• Imaging investigations such as CT scan to rule out any tumor that may be contributing to anemia
• Stool examination for ova and cyst

DISORDERS OF IRON EXCESS
• In certain inherited conditions of iron overload, called hemochromatosis, excess iron is deposited in various organs including liver, heart, skin, and kidneys resulting in tissue damage
• Other situations that may cause iron overload include conditions necessitating regular blood transfusions such as thalassemia


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PostPosted: 29 Sep 2019 14:04 
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Joined: 26 Feb 2013 10:59
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Its a good article on Iron metabolism. I would add a note to include sources of Iron:

Sources of Heme Iron: Animal proteins in our diet - Meat, Poultry, Seafood, and Fish,

Sources of Non-heme iron: Found in plant-based foods - grains, beans, vegetables, fruits, nuts, and seeds.
From animal products - Eggs and Milk.

I have often wondered where herbivores obtain their iron as they also need the iron for their haemoglobin. I am informed that iron deficiency in cattle is very rare as grass contain traces of iron and iron is abundant in the soil and most forages have some degree of soil contamination!


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