British Committee for Standards in Haematology clinical practice guideline recommends the following tests in patients with a suspected diagnosis of TTP:
Test
Comment
Complete blood count
Anaemia, thrombocytopenia
Peripheral smear
Schistocytes
Reticulocyte count
Increased
Haptoglobin
Reduced
Clotting screen including fibrinogen
Normal
Urea and electrolytes
+/- Renal impairment
Troponin T/Troponin I
For cardiac involvement
Liver function tests
Usually normal
Calcium
May reduce with TPE
Lactate dehydrogenase (LDH)
Increased
Direct antiglobulin test
Negative
Blood group and antibody screen
To allow provision of blood products
Pregnancy test
In women of child-bearing age
ADAMTS 13 assay ((activity/antigen and inhibitor/antibody in specialized laboratory)
Do not wait for result before starting treatment in suspected TTP
