Information
The haemoglobinopathies are categorised into two main groups: the haemoglobin variants and the Thalassaemia.
The haemoglobin variants arise from an alteration in the globin protein structure whereas the Thalassaemias arise from inadequate production of the normal globin protein.
Sickle cell disorders often result in severe life threatening clinical symptoms. Those patients with B Thalassaemia major require regular blood transfusions to maintain life.
Sample requirements
- EDTA
- A Full Blood Count (FBC) is also required
Minimum volume
- Adult: 1.8ml
- Paediatric : 0.5ml
Turnaround time
3 days
Reflexing a request on a full blood count must be done within 48 hours.
Reference range
| Units | Male | Female |
|---|---|---|
| Hb A % | 96% – 98% | 96% – 98% |
| Hb A2 % | 1.5 – 3.5 | 1.5 – 3.5 |
| Hb F % | <1 | <1 |
| Hb S % | 0 | 0 |
A comprehensive report will be issued with haemoglobinopathy investigations
Precautions
Precautions will be taken when handling all blood samples but special precautions will be taken when dealing with High Risk. These samples should be marked with High risk stickers and the clinical details stated on the request form.
Known CJD and query CJD patients will only be analysed after agreement with the Consultant Haematologist who will then advise the laboratory of which tests are required.
Limitations
Samples taken during difficult venepuncture may give erroneous counts. Platelet counts are especially affected.
Occasionally EDTA (Purple FBC bottle) can cause platelets to clump, falsely lowering the platelet count. Sodium Citrate (Blue Coagulation bottle) can sometimes provide a more accurate platelet count. If this sample is requested by the lab, an EDTA and Sodium Citrate sample should be sent together as only the platelet count will be accurate on the Sodium Citrate sample due to dilution effect.
It may not be possible to provide accurate results on short, clotted or haemolysed samples. These may be rejected with an appropriate comment. Lipaemic samples will require special procedures to obtain accurate results, a slight delay in the turn around time may occur with these samples.
Samples must not be exposed to extreme temperature e.g. next to heat source, left in direct sunlight or frozen.
Analysing laboratory
Haematology Lab, James Cook University Hospital, Marton Road, TS4 3BW
Advice
For clinical advice please contact Dr Plews on extension 54381.
For laboratory advice please contact Lorna Grange, Debbie Cram, Carol Bean or Sam Nodding on extension 52637