Iron Metabolism&Iron Deficiency Flashcards
Much of the body’s iron is in circulating red cells
True or false
True
1mg of iron per 1ml
How is iron content regulated in the body❓
By modulating it’s absorption
Functions of iron
Oxygen carrier ie hemoglobin
Oxygen storage ie myoglobin
Energy production
•cytochromes
•krebs cycke enzymes
•DNA synthesis
Liver detoxification, cytochrome p450
If there’s such a thing as iron toxicity, describe its effect
It catalyses the conversation of hydrogen peroxide to free-radical ions which can attack cellular membranes, proteins and DNA
Related to cancers, cardiac toxicity etc
The distribution of iron goes as follows
- 4g, 35-45mg/kg body weight
- Normal diet- 20-30mg
- 1-2mg iron absorbed each day, only 10%
- RBC as hemoglobin-67%
- Muscles as myoglobin-3.5%
- Storage as ferritin(mainly in the liver, reticuloendothelial cells,bone marrow)-27%
- Heme proteins-2.2%
- Serum-0.1%
Where is iron absorbed❓
What are the forms in which it can be absorbed❓
What factors promote and inhibit iron absorption❓
- In the duodenum and proximal jejunum
As haem iron/organic form- Fe2+: animal source, easily absorbed, less abundant
As ionic iron/inorganic form- Fe3+: plant sources
2. ⬇️Fe absorption •EDTA •Tannates •Carbonates •Oxalates •Phosphates •Antiacites •Clay
⬆️Fe absorption •Ascorbic acid •Citric acid •Amino Acids •Sugars •Gastric secretion •HCl
Give a brief description of how iron is absorbed
- From diet to enterocyte
•DcytB (duodenal cyt B.): Fe3+ to Fe2+
•DMT (divalent metallic transporter): transport into cell
OR
•HCP1(Haem carrier protein): transports haem iron into enterocytes - Storage in enterocyte:
•Ferritin - Transport to plasma:
•Hephaestin(in gut) or caeruloplasmin(other cells): Fe2+ to Fe3+
- Ferroportin: to plasma
- Transferrin: iron binding protein in plasma, carries iron btwn gut, liver, bone marrow, macrophages
What is the main regulator of iron homeostasis❓
What mechanism does it use❓
Hepcidin: Hepatic bacteriocidal protein
25aa peptide
Inactivates ferroportin
Inhibits transport of iron into plasma
Iron lost in stool when gut cells shed
List the factors that influence the absorption of iron
Increased absorption: •⬇️dietary iron •⬇️body iron stores •⬇️hemoglobin •⬇️blood oxygen content •⬆️RBC production
*leads to
⬇️hepcidin production by liver
⬆️activity of DcytB and DMT1
Decreased absorption:
•systemic inflammation
*leads to ⬆️hepcidin production
Production of hepcidin is ⬆️ by iron deficiency and ⬇️by iron loading and inflammation
True or false
False, quite the contrary
Transferrin is ⬆️ in iron overload and ⬆️ in iron deficiency
True or false❓
Why❓
False
Free transferrin is less w iron overload due to binding and vice versa
Transferrin testing is also known as❓
What could show an increase or decrease in transferrin?
Total iron binding capacity
⬆️:
Low body iron stores
High estrogen states
⬇️: High body iron stores Malnutrition Chronic liver disease Congenital deficiency Protein losing states
Serum iron is a routine blood test usually increased in
Iron overload
Pregnancy
Recent iron ingestion
Serum iron is a routine blood test usually decreased in
Iron deficiency
Pre-menstrual
Inflammation
Iron overload presents with high iron and low transferrin
True or false
True
Transferrin saturation is the best serum market of increased body iron
True or false
True
⬇️serum ferritin conc is a good indicator of iron deficiency but is elevated in inflammation
True❓
True.
Iron can be lost…
Physiological:
Gut desquamation
Menstruation; 1mg/day
Pregnancy, lactation
Pathological:
Hemorrhage
Menorrhagia
Haematuria
List conditions that could lead to iron deficiency
⬇️Fe intake
⬇️Fe absorption: Achlorhydria Gastric resection Celiac disease(gluten sensitivity enteropathy) Pica
⬆️Fe loss: -GI Blood loss: Gastritis Peptic ulcer disease Esophagitis Inflammatory bowel disease(Crohn’s disease, ulcerative colitis) Diverticular disease Hemorrhoids Infections: Hookworm, schistosomiasis Neoplasms
Uterine fibroids Vascular anomalies Excessive menstrual blood flow-80ml/30mg of Fe Chronic blood loss Hemoglobinuria (Intravascular hemolysis)
⬆️Iron requirements: Infancy Pregnancy Lactation Menstruation (40ml per cycle)
Signs and symptoms of iron deficiency anemia
Tachycardia Palpitations Headache Lightheadedness Angina pectoris Pica Hair loss Pallor Glossitis Stomatitis Angular cheilitis Koilonychia Retinal hemorrhages Splenomegaly(rare)
What laboratory findings point to iron deficiency anemia?
⬇️iron ⬇️ferritin ⬆️transferrin ⬆️serum transferrin receptor ⬇️transferrin saturation Hypochromia, microcytosis ⬆️erythrocyte zinc protoporphyrin
What are the stages of iron deficiency❓
- Reduced iron stores
- Iron deficient erythropoiesis
- Iron deficient anaemia
How would you treat a case of iron deficiency anemia❓
-treat underlying cause
- Give oral iron
- 100-200mg/day oral in three/four doses, 1hr before meal
OR
- Give parenteral iron
- Iron sucrose (IV) or iron dextran (IM)
- Dose=[15-Hg(g/dL)][Weight(kg)3]
(1st response is ⬆️reticulocyte after 7-10days)
What laboratory findings are expected in anaemia of chronic disease❓
⬇️Iron absorption
⬇️Serum iron
⬇️transferrin
