Bleeding Tests

Question 1

Prothrombin time

Answer 1

Thromboplastin added to test extrinsic sys.
Given as ratio comp to control, INR.
Normal 0.9-1.2.
Tests for abn fac 1,2,5,7,10.
Prolonged by warfarin, vit K defic, liver dis, DIC.
If long look for liver dis or anticoag use.

Question 2

Activated partial thromboplastin time

Answer 2

Kaolin added to test intrinsic sys.
Tests for abn fac 1,2,5,8,9,10,11,12.
Normal 35-45 secs.
Prolonged by heparin, haemophilia, DIC, liver dis.

Question 3

Thrombin time

Answer 3

Thrombin added to plasmin to convert fibrinogen to fibrin.
Normal 10-15 sec.
prolonged by heparin, DIC, dysfibrinogenaemia.

Question 4

D dimer- fibrin degradat prod rel from cross linked fibrin dur fibrinolysis.

Answer 4

Occs dur DIC, DVT, PE.

Also inflammat eg infec or malig.

Question 5

Bleeding time

Answer 5

Tests haemostasis.
Make 2 small incisions to forearm.
Normal under 10 mins.
Rarely done. PFA 100 modern alt (pl func analyser)
Raised in von willebrands dis, pl disorders, low dose asp.

Question 6

DIC

Answer 6

Both PT and aPTT v high
Low pl
Incr D dimer

Question 7

Pl count

Answer 7

If low do FBC, film, clotting.

Question 8

Erythrocyte sedimentation rate

Not really a bleeding test

Answer 8

Sensitive but non specif indicator of dis.
How far RBCs fall through a col of anticoag blood in 1 hr.
Cert prots on RBCs cause sticking to each other causing faster falling.
High if inflamm (infec, RA, malig, MI), anaemia, macrocytosis. Also rises with AGE.
Low if eg polycythemia, microcytosis, sickle cell.