25- NA: Iron Deficiency

Question 1

define anaemia

Answer 1

a decrease in the number of RBCs or less than the normal quantity of Hb in the blood

a reduction in Hb = anaemia = reduction in oxygen carrying capacity

Question 2

describe the appearance of reticulocytes on a blood film. what’s their significance?

Answer 2

purple stained, oval, bigger than RBCs = are a sign of polychromasia as immature RBCs

presence indicates bone marrow is producing RBCs and they’re circulating to reach peripheral blood

Question 3

describe expected Hb levels through stages of development/ ages - what else needs to be considered?

Answer 3

new-borns = have a higher Hb conc - polycythaemia - as they have more maternal blood and came from a hypoxic state in utero

by 6 months = Hb levels have fallen to 110g/L

by 5 yrs = iron stores deplete as child isn’t eating much

by 12-14 yrs = reach adult Hb levels above 120g/L

need to consider:
- age
- biological sex = women have lower Hb levels
- menstruating or non-menstruating = Hb levels drop from 130 to 120g/L during periods
- pregnancy = drop to 110g/L from increase in circulating plasma volume

Question 4

what is erythropoiesis?

Answer 4

the process of RBC formation from haemopoietic stem cells in bone marrow differentiating into various

Question 5

list the requirements for appropriate erythropoiesis

Answer 5

genetic regulation, healthy bone marrow, regulatory signals, nutritional substances like iron, vitamin B12 and folate

• genetic regulation from bone marrow = has the right genetic info to produce RBCs
• healthy bone marrow environment = for RBC maturation
• regulatory signals = cytokines like erythropoietin, released in hypoxic conditions to stimulate RBC production
• nutritional requirements = iron for Hb synthesis, vitamin B12 and folate for DNA synthesis and RBC maturation

Question 6

what are the three groups of causes related to anaemia?

Answer 6

failure of RBC production (reticulocytopenic)
ineffective erythropoiesis
decreased RBC survival

Question 7

describe the causes that fall under decreased RBC survival

Answer 7

blood loss - internal or external

haemolysis - premature destruction of RBCs

reticulocytosis - increased release of immature RBCs in response to acute blood loss

Question 8

describe the conditions for ineffective erythropoiesis

Answer 8

can have the right nutritional requirements, wrong environment or genetic instructions

e.g. anaemia of chronic disease

Question 9

how can we differentiate the causes of anaemia?

Answer 9

differentiate by reticulocyte count

high reticulocyte count = bone marrow can produce blood cells, problems lie in loss of blood
- e.g. haemolysis, bleeding

low reticulocyte count = indicates bone marrow problem
- e.g. insufficient nutritional requirements, environment/ genetic issues

Question 10

name the three types of anaemia related to RBC size

Answer 10

microcytic
macrocytic
normocytic

Question 11

what is microcytic anaemia? what conditions fall under it?

Answer 11

microcytic anaemia = iron deficiency by insufficient RBC production, smaller and paler RBCs

causes/conditions:
- thalassaemia = globin chain defect causing deficiency within RBCs
- anaemia of chronic disease
- iron deficiency

Question 12

what is normocytic anaemia? examples of causes/ conditions that fall under it?

Answer 12

normocytic anaemia = anaemia with normal sized RBCs

causes/ conditions:
- anaemia of chronic disease
- aplastic anaemia
- chronic renal failure
- bone marrow infiltration
- sickle cell disease

Question 13

what is macrocytic anaemia? what conditions cause/ underlie it?

Answer 13

macrocytic anaemia = high MCV, larger than normal RBCs with a normal amount of Hb in each cell

conditions:
- myelodysplasia = bone marrow makes abnormal RBCs
- B12 and folate deficiency
- alcohol, drug induced
- liver disease

Question 14

importance of iron

Answer 14

for oxygen transport - component of heme, binds oxygen molecules

Question 15

how is dietary iron mainly absorbed in the body and what influences its absorption?

Answer 15

mainly absorbed in the duodenum

absorption is influenced by the body’s iron status = iron homeostasis regulates the amount of iron absorbed by the duodenum

Question 16

what is the form in which iron circulates in the body, and what protein binds to it for transport?

Answer 16

circulates in the body in the form of Fe3+ bound to plasma transferrin

Question 17

where is most of the iron stored in the adult human body?

Answer 17

most of the iron in the adult human body is found in red blood cells

some is stored in:
- parts of the reticuloendothelial system - e.g., macrophages, spleen, liver
- bone marrow
- muscle myoglobin

Question 18

how is iron lost from the body, and what is the average daily loss?

Answer 18

lost mainly through mucosal sloughing, also through bleeding, desquamation or menstruation, and other forms of blood loss

average daily loss of approximately 1-2mg

Question 19

compare iron loss between menstruating and non-menstruating women, and men

Answer 19

men and non-menstruating women lose about 1mg of iron per day

menstruating women lose more = averaging 10mg of iron loss

premenopausal women have lower iron stores from recurrent blood loss during past menstruation

Question 20

what role do reticuloendothelial macrophages play in iron recycling?

Answer 20

important in iron recycling

they engulf senescent red blood cells, catabolize haemoglobin to scavenge iron, and then load the iron onto transferrin for reuse

Question 21

what are the two stable oxidative forms of iron, and what are their physiological roles?

Answer 21

two stable forms of iron:
- ferric (Fe3+)
- ferrous (Fe2+)

different states important for different physiological processes

Question 22

main function of haemoglobin (Hb) in iron metabolism? how many oxygen molecules can each heme group bind?

Answer 22

• major reservoir for iron in the body
• essential for oxygen transport

each heme group within Hb can bind to one oxygen molecule

Question 23

what are the storage proteins for iron, and how do they function?

Answer 23

storage proteins:
- ferritin
- hemosiderin

function:
- ferritin = acts as the main storage protein for excess iron, buffers and releases iron as needed by the body
- hemosiderin = another form of stored iron, primarily found in macrophages

Question 24

Which protein is responsible for transporting iron through the bloodstream, and what is its role?

Answer 24

transferrin

binds to iron and delivers it to cells throughout the body, facilitating iron distribution to where it is needed

Question 25

how are ferritin levels used clinically, and what do they indicate about the body’s iron status?

Answer 25

ferritin levels can be measured to assess the body’s iron stores

clinical evaluation helps determine the potential for iron deficiency or excess

Question 26

what are the three different states of iron?

Answer 26

within heme, as part of Hb

within storage proteins - ferritin and hemosiderin

in different oxidation states - ferric/3+ and ferrous/2+

Question 27

what is the role of hepcidin in iron metabolism, and where is it primarily produced?

Answer 27

produced by the liver

important in regulating iron homeostasis = controls the absorption, storage, and distribution of dietary iron in the body

Question 28

how does hepcidin regulate iron absorption in the gastrointestinal tract?

Answer 28

hepcidin binds to ferroportin receptors on enterocytes in the gut = limits the release of iron from these cells into the bloodstream

this reduces iron absorption and availability in the body

Question 29

factors that influence iron absorption in the body?

Answer 29

• types of iron ingested = heme vs non-heme
• dietary enhancers = e.g. vitamin C
• body’s iron storage levels
• bone marrow activity

Question 30

describe the mechanism by which hepcidin regulates iron transfer into blood plasma

Answer 30

hepcidin binds to ferroportin transporters on enterocytes, macrophages, and hepatocytes = induces internalisation and degradation of ferroportin

reduces iron transfer into the blood by:
- reducing absorption from the duodenum
- affecting macrophages involved in recycling senescent red cells
- affects iron storing hepatocytes

Question 31

how are hepcidin levels regulated in the body, and what is the impact of changes in hepcidin levels on iron absorption?

Answer 31

hepcidin levels are feedback-regulated based on:
- plasma and liver iron concentrations
- erythropoietic demand for iron

body needs more iron - hepcidin levels decrease = increased iron absorption

body has enough iron - hepcidin increases = decreases iron absorption, increases export

Question 32

what is the role of transferrin in iron transport, and where is iron primarily transported to when bound to transferrin?

Answer 32

transferrin = transport protein, binds iron in plasma and facilitates transport to tissues and bone marrow

mainly transported to developing red blood cell precursors in the bone marrow

Question 33

how does the body respond to iron deficiency? what changes are observed in transferrin and ferritin levels?

Answer 33

body increases transferrin levels to enhance iron absorption

ferritin stores are reduced as the body uses stored iron to meet its needs

Question 34

what is the function of ferritin in iron metabolism? how does the body utilize excess iron?

Answer 34

ferritin serves as an iron store in the body = storing excess iron that isn’t immediately needed

stored iron can be accessed whenever the body needs more iron for various physiological processes

Question 35

list the 5 lab studies used in assessing iron deficiency

Answer 35

serum iron
ferritin
transferrin saturation
transferrin
total iron binding capacity

Question 36

describe each of the 5 lab studies used in assessing iron deficiency

Answer 36

serum iron = assessing the amount of iron available in blood, variable and influenced by recent meals

ferritin = measures body’s reserve of stored iron as the primary iron storage protein

transferrin saturation = how much transferrin has iron bound to it

transferrin = production is inversely proportional to Fe stores, needed for Fe transport

total iron binding capacity =inverse of transferrin saturation, capacity of transferrin to bind iron

Question 37

expected results from the 5 lab studies in a case of iron deficiency anaemia - serum iron, ferritin, transferrin saturation, transferrin, total iron binding capacity

Answer 37

serum iron = low or normal

ferritin = low

transferrin saturation = low

transferrin = low - body increases transferrin production to compensate for iron deficiency

total iron binding capacity = high - higher value seen in iron deficiency when body’s trying to increase iron uptake

Question 38

which labatory iron study is used most reliably for confirming iron deficiency?

Answer 38

low ferritin is the key for an iron deficiency diagnosis = not may other causes for low ferritin

Question 39

describe the stages of development for iron deficiency anaemia

Answer 39

stages:
- normocytic and normochromic
- decrease in serum ferritin and symptoms
- latent iron deficiency
- depleting tissue iron stores
- iron deficient erythropoiesis
- delayed changes in MCV and MCH

initially normocytic and normochromic

serum ferritin starts decreasing, indicates decreased iron stores = show symptoms lie tiredness and hair loss

latent iron deficiency occurs where transferrin saturation takes longer to decrease, indicates iron deficiency

tissue iron stores start depleting, shown through abnormal lab study values

changes in haemoglobin occur further along iron deficiency as iron isn’t available - iron deficient erythropoiesis

MCH and MCV remain normal for several months after iron stores are depleted

Question 40

list clinical symptoms and signs of iron deficiency

Answer 40

symptoms:
- fatigue, lethargy, dizziness

signs:
- pallor of mucous membranes
- bounding pulse
- systolic flow murmurs
- smooth tongue
- spoon nails