Sample type: Serum
Test name: HIT a.k.a. Heparin Induced Thrombocytopenia PF4 antibodies
Condition / Indication: Requested when there is a high clinical suspicion of HIT. This is usually indicated by the 4T score. Type II HIT typically develops 5 to 14 days following treatment with unfractionated heparin (UFH). Low molecular weight heparin (LMWH) and, very rarely, fondaparinux have also been shown to cause HIT. In HIT heparin-dependent IgG antibodies bind to platelet factor 4 and activate platelets, resulting in thrombocytopenia and/or thrombosis.
Special precautions & notes: Requesting for HIT is available on ICE. If urgent please phone the haematology lab when sending the samples. All requests MUST be approved in advance by a Haematologist and accompanied by a 4T score; these details should be recorded in ICE or on a manual request form. An example 4T score calculator can be found below.
Container: Serum (gold top)
Referred outside NBT for analysis? Samples are referred to UHBW for screening. Negative results will be reported directly by UHBW. Samples with a positive screen will be referred on to NHSBT for confirmation and quantitation.
Discipline: Haematology
Turnaround time: 1 day for urgent requests, otherwise 5 days.
Referral location: Department of Haematology, Level 8 Queens Building, Bristol Royal Infirmary, Bristol, BS2 8HW NHS Blood and Transplant, Filton, North Bristol Park, Northway, Filton, Bristol BS34 7QH