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Year 2 - MCD Haem > Iron Deficiency > Flashcards

Iron Deficiency Flashcards

1
Q

Where is Iron normally found?

A

Found in many PROTEINS
inc. myoglobin, catalase, cytochrome P450 etc.

BUT most iron found in Hb

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2
Q

Link between Iron and Hb?

A

Low Iron = Low Hb = anaemia

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3
Q

What is the role of Iron in Hb?

A

Iron (specifically FERROUS) found in the
HAEM part
of Hb and its role is to hold onto O2

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4
Q

Iron homeostasis?

A

RBCs live for ~120 days!

Need around 20mg iron/day to replace lost RBCs
BUT
we can recycle iron!

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5
Q

How can iron be lost in the body?

A

o Desquamated cells of skin & gut

o Menstruation (bleeding)

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6
Q

How much iron do men and women need?

A

Men = 1mg/day

Women = 2mg/day

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7
Q

Where can we get iron from but what is an issue of this?

A
  1. Human diet
    o provides ~12-15mg/day
    o e.g. meat & fish (haem iron), veg, chocolate, whole grain cereal

BUT

most iron eaten is NOT absorbed
o can NOT absorb ferric iron (Fe3+)
o can only absorb ferrous iron (Fe2+)

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8
Q

How can you tackle the problem with iron absorption from diet? What makes it worse?

A

Orange Juice AIDS absorption of iron

Cups of tea makes it WORSE
o turns iron into the FERRIC form
o can lead to chronically low levels of FERROUS!

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9
Q

Factors affecting absorption of Iron?

A

Diet
o increase in haem iron (ferrous iron)

Intestine
 o acid in the duodenum
 o ligand (meat)

Systemic
o Iron deficiency (anaemia/hypoxia, preganacy)

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10
Q

Factors that INCREASE iron absorption?

A

Iron deficiency

Anaemia/hypoxia

Pregnancy

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11
Q

How is iron absorbed in the gut?

A
  1. Iron freely transports into the cell from the gut lumen
  2. FERROPORTIN facilitates transport of iron into the blood
    o HEPCIDIN inhibits ferroportin

Hepcidin is regulated
o has iron-responsive elements within their gene
o so iron part of complex that switches on its transcription

Ferroportin is found in
o enterocytes (dudodenum)
o macrophages (spleen)
o hepatocytes

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12
Q

How is Iron held onto in the circulation?

A

TRANSFERRIN!

  1. Iron taken into cells
  2. Protein shell forms around it
    o forms FERRITIN micelles
  3. Once iron enters plasma via. ferroportin, is linked to transferrin which transports it around the body
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13
Q

Characteristics of Transferrin and how it can be measured?

A

Usually 20-40% saturated with iron
o NEED it because iron is TOXIC & INSOLUBLE

o Transferrin levels
o Total Iron Binding Capacity (TIBC)
o Transferrin saturation
CAN all therefore be measured

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14
Q

Can TF enter cells directly?

A

NO
o bind with the TF-R and is internalised as a whole

As pH DROPS:
o iron is released
o TF-R are recycled

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15
Q

EPO?

A

Erythropoietin

Produced in kidneys
o production increased in response to hypoxia
o triggers more RBC precursors to be released
o the precursors survive longer and will survive, grow and differentiaite

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16
Q

ACD?

A

Anaemia of Chronic Disease

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17
Q

What is ACD?

A

Anaemia seen in patients who have a chronic disease

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18
Q

Cause of ACD?

A

Patient will NOT show classic causes of anaemia
i.e. bleeding
bone marrow infilitration
have a iron/B12 or folate deficiency

There is NO obvious cause

19
Q

Laboratory signs of ACD?

A
  1. Higher levels of C-reactive protein (CRP)
    o an acute phase protein (inflammation/infection)
  2. Higher Erythrocyte Sedimentation Rate (ESR)
    o rises in inflammation/infection
  3. Acute phase response - increases in:
 o Ferritin 
(usually reflects iron stores BUT is acutely ill levels shoot up as an acute phase protein so no longer good measure of iron during acute illness)

o F8
o Fibrinogen
o Igs (esp. IgG)

20
Q

Conditions associated with ACD?

A

o Chronic infections e.g. TB/HIV

o Chronic inflammation

o Malignancy

o Miscellaneous e.g. cardiac failure

21
Q

What normally causes the pathogenesis of ACD?

A

Due to CYTOKINE release

e.g. TNFalpha & ILs

22
Q

How does this pathogenesis demonstate itself in ACD?

A

The cytokines:
o prevent usual flow of iron from dudodenum to RBCs

o stop EPO increasing
o stop iron flow out of cells
o increase ferritin production
o increase RBC death

SO makes less RBCs = more RBCs die = less iron available

23
Q

Major cause of iron deficiency?

A

BLEEDING

e.g. menstrual OR GI

24
Q

Minor causes of iron deficiency?

A

Increased use of iron
e.g. growth/pregnancy

Dietary deficiency
e.g. vegetarian

Malabsorption
e.g. coeliac

25
Q

What type of investigation do you do if suspect iron deficiency?

A

Full GI investigation

26
Q

When should an investigation be carried out if suspect iron deficiency?

A

Good diet & NO coeliac Abs

o MALE

o Woman

  • over 40
  • post-menopausal woman
  • woman w scanty menstrual loss
27
Q

What is involved in the investigation for possible iron deficiency suspection?

A

A FULL GI investigation

o Upper GI endoscopy (oesophagua, stomach, dudodeum)
o dudodenal biopsy
o colonoscopy

If found NOTHING, do a small bowel meal and follow through

28
Q

What are other possible investigations if suspect iron deficiency?

A
  1. Menstruating women <40 years
    o if heavy periods OR multiple pregnancies
    o NO GI symptoms
    o DO NOTHING!!
  2. Check for urinary blood loss
  3. Abs for coeliac disease
29
Q

What are the laboratory parameters important when checking for iron deficiency?

A
  1. MCV
  2. Serum iron
  3. Ferritin
  4. Transferrin (TIBC)
  5. Transferrin saturation
30
Q

CASE STUDY!

Mrs Jones:
Hb = 100g/L
MCV = 72

What does this show?

A

BOTH are LOW

Hb NR = 120-150

MCV NR = 80-100

31
Q

CASE STUDY!

Is Mrs Jones iron deficient? Why?

A

Cannot tell as there are 3 causes of a low MCV

  1. Iron deficiency
  2. Thalassaemia trait
  3. ACD (could also have had normal MCV for this!)
32
Q

CASE STUDY!

Next parameter shows her Serum Iron is LOW

Is she iron deficient? Why?

A

NO - but can rule our thalassaemia trait!

In thalassaemia trait, serum iron is NORMAL
o to confirm would normally carry out Hb electrophoresis
o confirms an additional type of Hb present

Iron deficiency & ACD would both show LOW serum iron

33
Q

CASE STUDY!

Next parameter shows Ferritin LOW

Is she iron deficient? Why?

A

Ferritin NR (10-200)

Ferritin is:
o LOW in iron deficiency
o HIGH in chronic diease

34
Q

CASE STUDY!

Is ferrtin a good indicator for iron deficiency?

A

NO - as she could have underlying CD & iron deficiency
e.g. RhA with a bleeding ulcer

In this case, ferritin can be normal DESPITE iron deficiency

35
Q

CASE STUDY!

What lab tests can then be done to shows that ferritin is not ideal?

A 
CRP = RAISED
ESR = RAISED

Shows that there is some acute condition that is causing a rise in all the acute phase proteins
SO
ferritin can NOT be relied upon

36
Q

CASE STUDY!

Next parameter shows transferrin saturation which is at 4%

What does this show?

A

Transferrin sat. NR = 20-40%

Transferrin:
o INCREASES in iron deficiency
o NORMAL or LOW in ACD

Transferrin sat.:
o LOW in iron deficiency
- as more transferring & less iron

o NORMAL in ACD
- as iron & transferrin have BOTH gone down so saturation is normal

37
Q

CASE STUDY!

So what does Mrs Jones have?

A

Iron Deficient Anaemia

38
Q

CASE STUDY!

What further investigations could you do for Mrs Jones after assessing the diagnosis

A

Remember, the parameters on blood tests may show both iron deficiency & ACD so need to do further tests to discover source of bleeding!

o Endoscopy/colonoscopy
o Duodenal biopsy
o Anti-helicobacter Abs
o Anti-coeliac Abs
o Other
 - inc. abdo ultrasound (kidneys), dipstick urine, pelvic US to excluse fibrosis
39
Q

Man of ANY AGE with a LOW ferritin?

A

Does suggest iron deficiency!

Needs to have a upper and lower GI endoscopy to look for a source of bleeding

40
Q

Classic iron deficiency:

Hb
MCV
Serum iron
Ferritin
Transferrin
Transferrin sat.
A

Hb = LOW
MCV = LOW
Serum iron = LOW
Ferritin = LOW

Transferrin = HIGH
Transferrin sat. = LOW

41
Q

Classic ACD:

Hb
MCV
Serum iron
Ferritin
Transferrin
Transferrin sat.
A

Hb = LOW
MCV = LOW or N
Serum iron = LOW
Ferritin = HIGH or N

Transferrin = N or LOW
Transferrin sat. = N

42
Q

What does this suggest and extra test?

Hb = 10
MCV = 66
Serum iron = N
Ferritin = N
Transferrin = N
Transferrin sat. = N
A

Thalassemia trait!

Hb = LOW
MCV = LOW 
Serum iron = N
Ferritin =  N
Transferrin = N
Transferrin sat. = N

If iron deficiency OR ACD, serum iron would also be LOW!

Would do Hb electrophoresis to confirm!

43
Q

What does this suggest?

Hb = 10
MCV = 78
Serum iron = LOW
Ferritin = N
Transferrin = LOW
Transferrin sat. = N
A

RhA with bleeding ulcer!

Hb = LOW
MCV = LOW 
Serum iron = LOW
Ferritin =  N
Transferrin = LOW
Transferrin sat. = N

Year 2 - MCD Haem (11 decks)

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