Iron Deficiency Anaemia Flashcards
What are the functions of a RBC? [2]
oxygen delivery (haemoglobin is able to reversibly bind O2 without undergoing oxidation or reduction)
CO2 removal (involves RBCs, renal tubules and lungs)
What is the total body iron (Fe) content? [1]
4g
What are the uses of iron within the body? [4]
- bone marrow & RBCs
- reticular-endothelial system (RES)
- myoglobin
- enzymes
Describe the features of the plasma protein transferrin (Tf) [6]
- glycoprotein
- synthesised in the liver
- levels of plasma Tf is inversely proportional to levels of iron (low iron → high Tf)
- it has 2 iron binding domains
- only 4mg of iron can be bound at any one time
- Tf delivers iron to all tissues including erythoblasts, hepatocytes, muscle cells etc.
What is the relationship between serum ferritin levels and RES iron levels? [1]
serum ferritin levels is directly proportional to RES iron
1mmol/l serum ferritin = _____mg RES iron? [1]
8mg
Describe the process of iron absorption via the enterocyte [6]
- Haem iron is easily absorbed into the enterocyte into haem oxygenase
- Non-haem iron is released from food by acid digestion and proteolytic enzymes in the stomach
- Non-haem iron = Fe3+ (ferric form) is reduced to Fe2+ (ferrous form) by duodenal cytochrome b1 (dCytb1) - this process is enhanced by vitamin C
- Fe2+ is taken into the enterocyte by divalent metal transporter 1 (DMT1) which is an electrogenic pump that is upregulated in iron deficiency
- In the enterocyte, some iron gets stored as ferritin or in mitochondria whilst some gets exported into the plasma by ferroportin (FPN) - this exportation process is regulated by hepcidin (Hp).
- In the plasma, Fe2+ is converted back into Fe3+ to be transported through the plasma by transferrin (Tf)
How is RES iron stored? [2]
ferritin
haemosiderin
Describe how iron metabolism is regulated by hepcidin [5]
- it is the “low iron” hormone - it reduces the levels of iron in plasma
- hepcidin binds ferroportin and degrades it
- results in reduction in iron absorption in the enterocyte
- decreases iron release from the RES
- hepcidin is synthesised in the liver (this requires expression of HFE)
What condition is caused by loss of hepcidin? [1]
hereditary haemochromatosis
What are the 4 causes of hypochromic microcytic RBCs? [4]
- iron deficiency anaemia (not enough haem)
- thalassaemia (not enough globin)
- anaemia of chronic disease (ACD)
- sideroblastic anaemia
What is the relationship between serum ferritin and iron deficiency anaemia? [1]
low serum ferritin always indicates low RES iron stores
How can IDA occur with normal serum ferritin levels? [2]
ferritin is an acute phase protein, so in the presence of tissue inflammation (e.g. rheumatoid arthritis and inflammatory bowel disease), IDA can occur with normal serum ferritin levels
What are the 3 causes of iron deficiency anaemia? [3]
- dietary causes (esp. in premature neonates and adolescent females)
- malabsorption
- blood loss
What are the signs & symptoms of iron deficiency anaemia? [4]
- pallor (buccal membranes/conjunctival membranes/palmar creases/nail beds)
- koilonychia
- atrophic glossitis
- angular stomatitis
What are the golden rules when identifying the cause of IDA? [2]
- in males & post-menopausal women
- GI blood loss (until proven otherwise)
- in young women
- menstrual blood loss +/- pregnancy
List 3 serum parameters that you should measure in order to confirm the diagnosis of iron deficiency anaemia and state whether the parameter would be elevated, lowered or normal [3]
- serum iron
- lowered
- serum ferritin
- lowered
- serum total iron binding capacity (TIBC) - transferrin
- elevated
