HRU, Haematology Dept., UCL
Blood collection for ADAMTS13 assays
Equipment
 5ml 0.105M (or 0.109M) siliconised glass or plastic sodium citrate tubes (Vacutainer
or similar), 0.5ml citrate plus 4.5ml blood.

5ml empty glass tubes (Vacutainer or similar) for clotted blood (nb. Required for UK
TTP Registry Samples ONLY!)

1.5-2ml cryotubes with flat base (eg. 2.0ml micro tubes, Cat No. 72.694.007,
Sarstedt Ltd)

Polypropylene transfer pipettes
Procedure
1. Blood should be collected by clean venepuncture, using 19-21 gauge needles, into
a 5ml citrate tube. Minimal stasis should be applied, with free flowing blood.
Butterfly type needles may be convenient where multiple sample types are being
collected. If blood must be collected through an indwelling cannula, this should be
flushed with saline or balanced salt solution and the first 5-10ml blood discarded (try
to avoid lines that have contained heparin).
2. Citrate tubes must be mixed immediately, by gentle inversion 5-6 times and then
stored at room temperature.
3. Blood should be centrifuged within 4 hours of collection.
4. Citrate tubes should be centrifuged for 15 minutes, at 2000g, at room temperature
(18-20°C). After centrifugation, the plasma should be removed (avoiding
disturbance of the buffy coat) using a polypropylene transfer pipette into 4 x 0.5ml
aliquots in cryotubes. If the buffy coat is disrupted, centrifuge the tube again and
repeat the process.
5. Clotted blood tubes should be centrifuged for 10 minutes, at 1500g, at room
temperature (18-20°C). After centrifugation, the serum should be pipetted into 2 x
0.5ml aliquots in cryotubes.
6. Label all tubes (using a permanent marker) with the patient name and date of
collection (patient study number/code where appropriate). Clearly mark whether
“Plasma” or “Serum”.
7. Freeze plasma aliquots at –70°C (if local storage is only available at -20°C, ensure
that the aliquots freeze rapidly and transfer them to a –70°C freezer within 2
weeks).
8. At a suitable date, arrange the transfer of the plasma and serum aliquots on dry ice,
to the Haemostasis Research Unit, UCL Haematology Dept., 1st Floor, 51 Chenies
Mews, London WC1E 6HX; Tel 020 7679 6416/ 21/ 22/ 23.
Haemostasis Research Unit
Jan 2009