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HEMATOLOGY > MACROCYTIC ANAEMIA > Flashcards

MACROCYTIC ANAEMIA Flashcards

1
Q

Define macrocytic anaemia.

A

anaemia in which hthe red cells have a LARGER than normal volume

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2
Q

How to measure MCV?

A
  • modern analyser use LIGHT scatter properties of the red cells
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3
Q

What to compare the size of the red cell on blood film?

A
  • compare to the nucleus of a small, mature lymphocyte

- —should be the SAME size

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4
Q

precursor Red cell with nucleus.

A
  • erythroblasts/normoblasts

- DO NOT circulate in the periphery

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5
Q

Loss of nucleus in red cell with a small amount of RNA; circulates in the periphery.

A
  • RETICULOCYTE (why they appear bluer)
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6
Q

What changes occur to result in a mature red cell.

A
  • primitive erythroblasts - will start to accumulate Hb> cell will REDUCE in size and INCR. in nuclear maturation
  • —–when Hb conc. reaches a critical stage; cell will stop dividing and nucleus is lost
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7
Q

Which precursor red cell goes through anucleation and why?

A
  • Late Normoblast

- —-d.t peak accumulation of Hb

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8
Q

How does a megaloblastic cell appear?

A

an ABNORMALLY LARGE nucleated red cell precursor with an IMMATURE nucleus

  • open chromatin
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9
Q

WHAT IS KEY about MEGALOBLASTIC ANAEMIA?

A
  • the LACK of red cells d.t PREDOMINANT problems with DNA maturation and synthesis
  • —-BUT NORMAL HB and RNA synthesis
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10
Q

What occurs with cell division in erythroblasts; in megaloblastic anemia?

A
  • due to abnormal nucleus IN THE PROERYTHROBLAST

- — but in maturing erythroblasts; division is REDUCED and APOPTOSIS increases

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11
Q

WHy are B12 and folate important?

A
  • essential for biochemical reactions
  • —involved in DNA modification and GENE activity(NERVOUS SYSTEM impact); as well as DNA sysnthesis and nuclear maturation (blood cell defect)
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12
Q

Where is

A
  • rich in meat, eggs

Cobalamin

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13
Q

Where is B12 absorbed?

A

in the DISTAL GUT

—-those who had a distal bowel resection; may face B12 deficiency

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14
Q

Causes of vit. B12 def. in the stomach

A
  1. atrophic gastritis
  2. Pernicious anemia
  3. gastrectomy /bypass
  4. PPPIs and H2-R anatagonists
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15
Q

WHat occurs with pernicious anemia>

A
  • AUTOIMMUNE condition of destrc. of GASTRIC parietal cells

- —>IF deficiency with B12 malabsorption and deficiency

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16
Q

What may be the co-morbidites for PA?

A
  • a.w atrophic gastritis

- personal or family hx of other autoimmune conditions (Hypothyroidism/ vitiligo/ addison’s disease

17
Q

WHen may folate deficiency present itself?

A
  • 4 months

- —-LOW stores in the body; store can easily be diminished

18
Q

Where is folate absorbed?

A
  • in the DUODENUM and JEJUNUM
19
Q

What are the causes of FOLATE defi.?

A
  • anticonvulsants drugs
  • HEMOLYSIS
  • EXOFOLIATING DERMATITIS
  • malignancy
  • pregnancy
  • alcoholics and alcoholics

—–crohn’s and celiac disease

20
Q

What are the clinical fts of b12/ folate def.?

A

Symptoms/signs of anaemia
weight loss, diarrhoea, infertility
Sore tongue, jaundice
Developmental problems

21
Q

Which def. may present with neurological problems?

A
  • Vit. B12 (may APPEAR NORMAL in labs)

posterior/dorsal column abnormalities, neuropathy, dementia, psychiatric manifestations

22
Q

How to dx with lab findings; B12-Folate def.?

A
  • Macrocytic anemia (RED cell count is LOW)
  • Pancytopenia (in some)

—-blood films show MACROOVALOCYTES and hypersegmented neutrophils

23
Q

What are other LAB ivx?

A
  • measure B12 and folate in the serum (not reliable)
  • check for AUTO-ABs (anti-IF/ anti gastric-parietal cell)
  • bone marrow exmam. and schilling’s test (no longer done)
24
Q

How to treat megaloblastic anaemia?

A
  • FOLIC acid oral tablets

- —-Vit. B12 (Hydroxycobalamin) INJECTIONS for life in pernicious anaemia

25
Q

Causes of non-megaloblstic macrocytosis (NOT a.w with anaemia) ?

A
  • alcohol

- liver disease and hypothyroidism

26
Q

Causes of non-megaloblstic macrocytosis - a.w with anaemia) ?

A
  • MARROW failure (MYELOMA/ aplastic anaemia/ myelodysplasia)
27
Q

Why may reticulocytosis cause FALSE incr. in MCV? -

A
  1. Reticulocytosis reticulocytes are BIGGER and mistaken as a red cell
    - –red cell mcv may be normal but because reticulocytes, avg MCV is thrown off
  2. Cold AGGLUTININS
28
Q

Can jaundice be seen with pernicious anaemia

A
  • YES d.t intramedulalry hemolysis —red cells DIE premature alt in the marrow; Hb and LDH are release from dead red cells
  • —Hb converts to bilirubin
29
Q

How does the macrocyte come about in Megaloblastic anaemia?

What occurs as a result of the shortcomings?

A
  1. cytoplasmic developm. and Hb accumulation is NORMAL
  2. like in normoblasts, ince optimum Hb is reached; nucleus is extruded from the cell —-leaving behind a BIGGER-THAN-NORMAL cell

——FEWER macrocytes AND hence ANAEMIA

30
Q

Why does large cell size result in MEGALOBLASTIC anaemia?

A
  • d.t FAILURE of the cell to get SMALLER; not due to an increase in size
31
Q

What causes megaloblastic anaemia?

A

B12 and FOLATE deficiency

—others: DRUGS/ rare inherited abnormalities

32
Q

Describe the manner by which Vitamin B12 is absorbed.

A
  1. d.t acidic pH in the stomach, B12 binds to Haptocorin and empties into the gut with IF (unbound)
  2. IN the DUODENUM and JUJENUM, pancreatic peptidases will cleave the complex and release B12
  3. B12-IF complex will then bind to the CUBULIN receptors found on the brush border of the gut mucosa
33
Q

What is the source of Folate?

A
  • LIVER
  • LEAFY veg
  • foritfied cereba;s
34
Q

How long till B12 stores deplete and where is ILEUM absorbed?

A
  • 2-4 YEARS

- ileum

35
Q

What is meant by spurious macrocytosis?

A
  • volume of mature red cell is NORMAL

- MCV is MEASURED as high

36
Q

Apart from reticulocytosis, what is the other cause of spurios macrocytosis?

A
  • cold AGGLUTININS
    (causes clumping of the red cells at room T*)
    —-clumped groups are read as one red cell
    ——-read as having an MCV of 150 !

HEMATOLOGY (20 decks)

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