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Hematology week 1 > Megaloblastic Anemia > Flashcards

Megaloblastic Anemia Flashcards

1
Q

a group of anemia’s in which the erythroblasts in the bone marrow show a characteristic abnormality- maturation of the nucleus being delayed relative to that of the cytoplasm.

A

Megaloblastic Anemia

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2
Q

Megaloblastic Anemia is a Macrocytic anemia (MCV more than 98fL), that results from defect in DNA synthesis in developing RBC due to deficiency

A

of B12 and folic acid

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3
Q

Less common causes Megaloblastic Anemia

A
  • Abnormalities of vit. B12 or folate metabolism.
  • Other defects of DNA synthesis (congenital or acquired enzyme deficiency)
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4
Q

Vitamin B12 is synthesized by

A

bacteria and found in foods of animal origin.

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5
Q

The estimated average requirement for B12 in adults is

A

1–2 micrograms/day

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6
Q

The main site of absorption of b12

A

the terminal ileum

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7
Q

how is b12 stored

A

It is stored mainly in the liver (2-3 mg) which is sufficient for 2-4 years before it gets depleted

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8
Q

Most of the B12 in food is protein-bound and is released when the protein is subjected

A

to acid peptic digestion in the stomach

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9
Q

B12 -IF “Cbl-IF” complex bind to receptor (cubilin) at

A

distal ileum for mucosal absorption

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10
Q

transport protein involved in delivering vit B12 to bone marrow and other tissues (functional B12)

A

Transcobalamine II

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11
Q

storage protein (non functional B12)

A

TCI (haptocorrin)

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12
Q

The total amount of B12 in the body

A

is 2–3 mg, mostly stored in liver

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13
Q

The commonest cause for Cobalamine deficiency (due to impaired absorption)

A

Pernicious anemia

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14
Q

what is The definitive test for the diagnosis of pernicious anemia

A

SCHILLING TEST

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15
Q

Pernicious anemia CLINICAL FEATURES

A
  • Mild jaundice.
  • Angular stomatitis and mild symptoms of Malabsorption with loss of weight due to epithelial abnormality.
  • Atrophic glossitis- “beefy” tongue.
  • Neurological disorders due to defective methylation of myelin.
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16
Q

Lab Findings Mild to severe anemia (7)

A

1- Increased MCV & MCH, normal MCHC
2- Low RBC, HGB, WBC and PLT counts (fragile cells) due to ineffective hematopoiesis.
3- Low reticulocytes count
4- Macrocytic ovalocytes and teardrops.
5- Marked anisocytosis and poikilocytosis.
6- Schistocytes due to RBC breakage upon leaving the BM
7- Hypersegmented Neutrophils

17
Q

BONE MARROW in Megaloblastic anemia

A
  • Markedly hypercellular
  • Myeloid : erythroid ratio decreased or reversed
  • Erythropoiesis : MEGALOBLASTIC
18
Q

what is the normal M:E ratio

A

3:1

19
Q

Biochemical tests for assessing B12 status

A
  • High unconjugated bilirubin.
  • High LDH.
  • Low total serum B12.
  • High methylmalonic acid (MMA), which is highly specific for B12 deficiency, being more specific than a low serum B12.
  • High plasma total homocysteine (poor specificity).
  • Auto antibodies screening (IF and Parietal cells AB).
  • Schilling test.
  • 60% of B12 -deficient patients have low red cell folate levels.
20
Q

Folates are found in foods

A

of both animal and vegetable origin.

21
Q

The estimated average requirement for folate in adults is

A

100–150 micrograms/day

22
Q

It can be easily destroyed by cooking

A

folic acid

23
Q

The main site of absorption of folic acid is

A

is the jejunum

24
Q

what happens in the jejunum

A

folic acid will be converted to methyl tetrahydrofolate ( methyl THF)

25
Q

Causes of Folate deficiency

A

A)Decreased intake

B)Malabsorbtion

C)Increased demands

D) Drugs

26
Q

folate deficiency due to decreased intake

A

Alcoholism
Hyperalimentation
Hemodialysis
Prematurity
Synthetic diet feeding Goat’s milk feeding

27
Q

folate deficiency due to Malabsorbtion

A

Nontropical sprue
Tropical sprue
Intestinal resection
Other intestinal diseases

28
Q

folate deficiency due to Increased demands

A

Pregnancy
Chronic hemolytic diseases
Myeloproliferative diseases
Dermatitis(expholiat.)
Hyperthyroidism

29
Q

folate deficiency due to Drugs

A

Oral contraseptive drugs
Some anticonvulsant drugs
Cholestyramine

30
Q

Clinical features of folate deficiency

A

Very similar to B12 deficiency.
* Differs from B12 deficiency in that it does not cause the sub acute combined degeneration of the spinal cord.
* Treatment with folic acid to patients with Megaloblastic anemia and neuropathy due to B12 deficiency will improve the degree of anemia but not the neuropathy.

31
Q

Laboratory findings in Folate deficiency

A
  • Lab and BM findings are identical to B12 deficiency.
  • In biochemical tests: Low Serum folate. Low RBC folate
  • Homocysteine level is elevated in both folate and B12 deficiency
  • Methylmalonic acid level is normal in folate deficiency.

Hematology week 1 (5 decks)

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