Heparin

Question 1

two main types of heparin ?

Answer 1

unfractionated, ‘standard’ heparin or low molecular weight heparin (LMWH)

Question 2

heparins generally act by ?

Answer 2

activating antithrombin III

Unfractionated heparin forms a complex which inhibits thrombin, factors Xa, IXa, XIa and XIIa.

LMWH however only increases the action of antithrombin III on factor Xa

Question 3

adverse effects of heparin ?

Answer 3

bleeding

thrombocytopenia - HIT

osteoporosis and an increased risk of fractures

hyperkalaemia - this is thought to be caused by inhibition of aldosterone secretion

Question 4

which type of heparin has a lower risk of side effects ?

Answer 4

LMWH

Question 5

which form of heparin has a longer duration of actin

Answer 5

LMWH

Question 6

how do we monitor heparin ?

Answer 6

Activated partial thromboplastin time (APTT)

Question 7

how do we monitor LMWH ?

Answer 7

Anti-Factor Xa (although routine monitoring is not required)