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MET3B > Erythropoiesis & Microcytic Anaemia > Flashcards

Erythropoiesis & Microcytic Anaemia Flashcards

1
Q

Where does hematopoiesis occur in the first few weeks of life?

A
  1. Yolk Sac transient 2. Fetal liver Liver, 3.spleen, 4.bone marrow
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2
Q

Where does hematopoiesis mainly occur from 6 weeks- 7 months of life?

A

liver & spleen major contributors, Placenta may contribute

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3
Q

What is the major contributor to hematopoiesis from 6-7 months?

A

Bone marrow is the major contributor

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4
Q

Where does hematopoiesis mainly occur during infancy?

A

All bones

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5
Q

What happens to bone marrow from infancy to adult life?

A

In infancy it is present in all bones As you age, there is fat displacement. In adult life marrow is only located in the central skeleton and the proximal ends of femerus and humeri

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6
Q

Describe the stages of erythropoiesis

A
  1. Proerythroblast- Synthesis of hemoglobin starts 2. Early normoblast- Nucleoli disappears basophilic erythroblast 3. Intermediate normoblast- Hemoglobin starts appearing giving rise to polychromatophilic erythroblasy 4. Late normoblast- nucleus disappears resulting in orthochromatic erythroblast 5. Reticulocyte- Reticulum is formed, resulting in polychromatophilic erythrocyte. Cell enters the capillary from side of production. 6. Mature RBC- reticulum disappears and cell attains bioconcavity.
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7
Q

What are the progenitor cells for red blood cells?

A

Multipotential progenitor- CFU-GEMM Commited progenitor- BFU-E then CFU-E.

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8
Q

Function of growth factors in the formation of red blood cells? Where are they produced?

A

Function- glycoprotein hormones that regulate proliferation and maturation Most are produced by stromal cells apart from Epo, 90% of which is synthesized in kidneys and Tpo in liver

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9
Q

Where in the kidneys is Erythropoietin produced? Which cells produce it

A

Outer cortex of the kidneys- Produced by peritubular interstitial cells

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10
Q

What stimulates the production of Erythropoietin in the kidneys?

A

Hypoxia in the kidneys and proximal tubules. This is bceause Oxygen levels in and around the proximal tubule are not altered by exercise or changes in blood pressure. Only determined by level of haemoglobin in the arterial blood

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11
Q

Which changes does hypoxia in the kidneys induce to increase red blood cell production?

A
  1. stimulates erythropoietin production 2. stimulates new vessel formation 3. transferrin receptor synthesis 4. increasing iron absorption
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12
Q

What decreases erythropoietin production?

A

High red cell mass or increased delivery of O2 decreases its production

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13
Q

How much iron is absorbed and excreted each day?

A

1 mg is absorbed and 1 mg excreted each day

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14
Q

How much iron does the average diet contain?

A

15mg iron / day

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15
Q

Where is most of the Iron in the body located?

A

Found in circulating haemoglobin some stored in ferritin

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16
Q

What is the total amount of iron contained in the body?

A

3–5 g

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17
Q

Where is most of the iron from food absorbed? Which cells absorb them?

A

in the duodenum by enterocytes

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18
Q

Iron can only be absorbed in 2 forms? What are they?

A

ion (Fe++) - ferrous form or as part of a protein such as heme protein

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19
Q

Describe the absorption and transport of iron in the duodenum?

A

Enterocytes in the duodenum have transporter proteins- ferroportins to absorbed Iron. A ferric reductase enzyme on the enterocytes’ brush border can reduce Fe3+ in the gut lumen to Fe++ Iron is taken up from the enterocytes by transferrin and transported in the blood to the bone marrow and other cells Transferrins loaded with iron can bind to transferrin receptors on the surface of a cell. They are then transported into the cell in vesicles via endocytosis. Inside the cell endosome a low pH makes the transferrin release its iron ions. They are taken up by haemoglobin or ferritin molecules which store the iron for future use. The empty receptor/transferrin complex is transported back to the cell surface and the transferrin is released

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20
Q

What is transferrin? What is its function?

A

iron-binding blood plasma glycoproteins regulate the level of free iron in plasma and other extracellular fluids.

21
Q

How much iron can transferrin bind to?

A

Can carry two iron atoms in the ferric form

22
Q

Describe the structure and function of ferritin

A

very large hollow ‘polyprotein’ made of 24 apoferritin subunits stores many iron atoms inside it in the inactive (Fe+++) form

23
Q

How can ferritin concentration be used diagnostically?

A

A small amount is found in blood serum and functions as an indirect marker for the total amount of iron stored in the body. Can be used to diagnose iron deficiency anemia

24
Q

Where will you mostly find ferritin in the body?

A

Within tissues as a cystolic protein

25
Q

What is the definition of anemia?

A

A reduction in the haemoglobin concentration below the normal range for age and sex

26
Q

List 5 symptoms of anaemia

A

Weakness Lethargy Palpitations Headaches Cardiac failure- in elderly

27
Q

List and describe the signs of anaemia

A

General – Pallor of Mucous membranes or nail beds A hyperdynamic circulation – tachycardia, bounding pulse, cardiomegaly, flow murmur Specific – Koilonychia (flat concave nails), jaundice, leg ulcers, bone deformities, associated excess infections, spontaneous bruising

28
Q

What is the normal MCV range? 80-95fL

Produce a diagnostic flow diagram detailing the diagnosis of anemia using MSV value

A
29
Q

What type of cell is this? What are the causes of this kind of anaemia?

A

They are target cells (condocytes)

Causes- Iron deficiency

Liver disease

post-splanectomy

Heamhoglobinopathies (thalassaemia)

30
Q

What type of cell is this? What are the causes of this kind of anaemia?

A

Stomatocyte

Liver diease and alcoholism

31
Q

What type of cell is this? What are the causes of this kind of anaemia?

A

Sickle cell

Cuased by the presence of heamoglobin S - sickle cell disease and haemoglobin SC disease

32
Q

What type of cell is this? What are the causes of this kind of anaemia?

A

Tear drop cell

Caused by myelofibrosis, megaloblastic anaemia

33
Q

What type of cell is this? What are the causes of this kind of anaemia?

A

Spherocytes

Causes:

Immune heamolytica anaemia

Severe burns

Hereditory spherocytosis

post- splanectomy

34
Q

What type of cell is this? What are the causes of this kind of anaemia?

A

Eliptocyte

Hereditory eliptocytosis

Some heamoglobinopathies

Iron deficeincy

mylofibrosis

Megaloblastic anaemia

35
Q

What type of cell is this? What are the causes of this kind of anaemia?

A

Ovalocyte

Causes

  • Asian ovalocytosis
  • macro ovalocytes indicate impared DNA synthesis e.g. B12 and folate deficiency
36
Q

What type of cell is this? What are the causes of this kind of anaemia?

A

Irregularly contracted red cell

Causes:

  • Heamoglobinopathies
  • Oxidative damaged
37
Q

What type of cell is this? What are the causes of this kind of anaemia?

A

Keratocyte

Causes:

Microangiopathic heamolytic anaemia

Intravascular coagulation

38
Q

What type of cell is this? What are the causes of this kind of anaemia?

A

Schistocyte

Microangiopthaic and mechanical haemolytic anaemia

39
Q

What are the causes of Microcytic Hypochromic Anaemia?

A
  • Iron Deficiency
  • Anaemia of Chronic Disease
  • Lead Toxicity
  • Sideroblastic Anaemia
  • Thalassaemia
40
Q

Name 2 significant findings indicating iron deficiency anaemia

What are the general signs of anemia in children?

A

Koilonychia

Angular stomatitis

Children-

Irritability

Poor cognitive function

Decline in psychomotor development

41
Q

List the main causes of iron defeincy anaemia

A

Pregancy (increase demand plus lactation)

Child hood (increase demand)

Blood loss- (Menorrhagia, inflammatory bowel disease, peptic ulcer diease, GI malignancies)

Poor iron intake- vegan diet

Poor absorbtion- Gastric Bypass surgery, Gastro oesophageal reflux disease, gastritis, H-pylori, Antacid/PPI use, High caffine consumption, celiac disease, parasite infection

42
Q

Which type of anemia is caused by blood donations?

A

Iron deficiency

43
Q

How does pregancy lead to iron deficiency anaemia?

A

300mg of iron is transfered from mother to feotus

Blood loss at delivery

Red cell mass needs to increase by 35% to cope with this

44
Q

What is the medical term for periods? How much blood is lost in each cycle?

A

Menorrhagia (> 80 mL loss per cycle)

45
Q

How long does it take for a poor diet or malabsorbtion to cause iron deficiency in a normal adult male?

A

8 years

46
Q

What is the treatment for Iron deficiency Anaemia?

A
  1. Improve Diet (include haem-containing proteins
  2. Iron tablets (ferrous sulphate)
  3. Avoid blood transfusion
  4. Once Hb normal continue iron supplements for ~3 months to replenish body iron stores
  5. Parenteral Iron
47
Q

What is the name of an iron supplemen, how should it be taken? What are the sie effects? What can be taken instead if side effects are too severe?

A

Ferrous Fumarate

Prescribed on an empty stomach in doses spaced by at least 6 hours

nausea, abdominal pain, constipation, diarrhoea

Take Ferrous Gluconate (less iron) instead

48
Q

What is Sideroblastic anaemia? What is the pathology dictating its presentation?

A

What- a form of anaemia characterised by the presence of ring sideroblasts in the bone marrow

Pathology- erythroid hyperplasia with ineffective erythropoiesis

  • Caused by a defect in Haem synthesis
  • Hereditary form – mutation in gene on X chromosome
  • Acquired form is more common – Subtype of Myelodysplasia
49
Q

List one main cause of Sideroblastic anaemia

Describe how it causes it and what you will find on the blood film

A

Lead poisoning inhibits both haem and globin synthesis

Basophilic stippling (accumulation of denatured RNA) is a feature on the peripheral film

MET3B (17 decks)

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