Anaemia

Question 1

Function of erythrocytes and their formation and destruction?

Answer 1

Carry O2
Haemopoetic stem cells - GF (erythropoietin) encourage differentiation and development.
120 days.
Aged RBCs engulfed by macrophages in reticulendothelial system of liver and spleen

Question 2

What is the Haemocrit?

Answer 2

volume of RBCs in blood as a percentage of total blood volume (approx 45%)

Question 3

Structure of Hb

Answer 3

4 x globin subunits (2 pairs)…each bound to a haem which contains ferrous Fe++ which binds O2.
4O2 molecules can bind altogether

Question 4

Define anaemia

Answer 4

reduced concentration of Hb in the blood

Question 5

Causes and symptoms of anaemia

Answer 5

Menstruation, pregnancy, dietary deficiency, bone marrow supression, excessive destruction of RBCs (haemolytic anaemia)

Question 6

What is microlytic anemia?

Answer 6

small RBCs, low Hb, iron deficiency

Question 7

What is macrolytic anaemia?

Answer 7

large, fragile, deformed RBCs, few in number, vit B12 and folic acid deficiency

Question 8

What is normolytic anaemia?

Answer 8

normal size RBCs, few in number, bone marrow supression

Question 9

What is the choice of drugs dependant on?

Answer 9

The underlying cause of the anaemia

Question 10

Iron…normal levels, loss and absorption..how is absorption enhanced/decreased?

Answer 10

70kg man…4g or iron…1.8g in Hb…800mg in liver, spleen and bone marrow.
1-2 mg lost per day Recycled, levels changed by changes in absorption. Iron in meat and fish = heam iron…best for absorption. Veg and pulses…non-haem iron.

Ascorbic acid - increase absorption…fe+++ reduced to fe++…and form soluble iron-ascorbate complexes

Tetracycline…decrease absorption. Form insoluble complexes. Decrease absorption of iron and antibiotic

Question 11

Most common causes of iron deficiency?

Answer 11

Excess blood loss - mestrutation, GI bleed
Increased utilisation - pregnancy
Poor absorption - tetracycline, GI disease

Question 12

Describe iron absorption

Answer 12

In duodenum, ferric iron is converted by ferric reductase to ferrous iron. Fe++ is then transported via the divalent metal transported 1 to the endothelial cells. Ferrous iron is then either converted to ferric iron and stored as ferritin (water soluble, stores 4500) or is transported to the blood along with haem iron which has been converted by haem oxidase to ferrous iron. Ferroportin transports Fe++ to the blood where is converted to ferric iron and then 2 fe+++ are added to apotransferrin to form transferrin which is moved to the bone marrow.

Question 13

Oral iron preparations - doses and side effects

Answer 13

Ferrous sulphate (200mg table with 65mg of iron) or ferrous gluconate

Side effects are dose related..mild nausea, diarrhoea or abdominal cramps

Question 14

Acute iron toxicity…when does it occur, symptoms and how is it treated?

Answer 14

Occurs in overdose
Severe gastritis with haemorrhaging, vommiting, diarrhoea and potential circulatory collapse.
Treated with iron chelators - desferrioxamine (binds excess iron and excretes it in urine).

Question 15

Role of VitB12 and Folic acid

Answer 15

DNA synthesis and cell proliferation therefore deficiency noticed as RBCs have a rapid turnover. Results in macrolytic anaemia.

Question 16

Vit B12 deficiency…leads to?

Intake of Vit B12?

Answer 16

leads to neurological disorders, usually due to lack of intrinsic factor (required for vit B12 absorption) - pernicious anaemia

liver eggs dairy
injected as hydroxocobalamin

Question 17

Folic acid (vit B9) deficiency?

Answer 17

Lack of intake during periods of high demand
Found in green veg, liver, fruit, yeast - need 200mg a day
enters cells as 5methylFH4

Question 18

Erythropoietin

Answer 18

glycoprotein hormone, formed in juxtatubular cells of kidney if low O2 or blood loss. Binds tyrosine kinase receptors to encourage RBC production

Side effects: Flu like symptoms, hypertension, iron defoniceny, icnreased blood viscosity leading to thrombosis.