Turnaround times
The quoted turnaround time is from sample receipt in the laboratory, to results authorisation in the Laboratory Information Management system. The times do not include transport of specimen to the laboratory or the administrative process to print and post/email reports. Service users must allow for transport and reporting time when ordering tests.
Clinical background:
Haemoglobin S (HbS) or sickle cell haemoglobin, results from an autosomal recessive mutation to the beta globin gene. Red cells containing HbS have a reduced deformability, under conditions of Hypoxia they form the so-called sickle shape and are easily destroyed resulting in occlusion of the microcurculation and a chronic haemolyitic anaemia. Heterozygotes have sickle cell trait, homozygotes have sickle cell disease. HbS may be found in conjunction with other Haemoglobin mutations and compound heterozygotes may display the features of homozygous disease or be asymptomatic depending on the combination. The screeing test will detect the presence of HbS in a sample, it will not distunguish between HbAS (heterozygote) and HbSS (homozgote), positive samples are sent for Haemoglobin Quantitation. The test is used as a quick pre-op screening test in patients with a family history of HbS or if the patient is from a region with a high prevelance of the mutation (Africa, Middle East, Mediterranean and India) as general anaesthesia presents a significant risk to paitents with this mutation.
Specimen container paediatric:
Purple EDTA
Specimen container adult :
Purple EDTA 4ml14 days if stored between 2 to 8 degrees
Minimum volume paediatric:
1.0mL
Minimum volume adult:
2.0mL
Special requirements:
Ensure adequate mixing.
Sample stability:
14 days if stored between 2 to 8 degrees
Transport requirements:
No Special transport requirements
Availability :
Always available- Testing completed by RVI Protein laboratory between 08:30 and 17:00, Testing completed by RVI Haematology laboratory between 17:00 to 08:30
Freq analysis:
Routine testing completed daily Monday to Friday, Urgent testing out of hours completed on request
Add on test:
Phone EXT 24766 during routine house and EXT 25819 out of hoursAll urgent add ons via telephone must be confirmed via email to the appropriate email address
[email protected] (internal)
Quality assurance:
The lab participates in the UKNEQAS Abnormal Haemoglobins EQA scheme
Interpretation:
Positive – Suggest Haemoglobin S presentNegative – Suggest Haemoglobin S not present.All results require confirmation via High Performance Liquid Chromatography via a Haemoglobinopathy screen. During routine hours, this will be completed by the Protein laboratory. If confirmation and haemoglobin S quantitation required urgently out of hours this must be discussed with the Biochemistry Biomedical Scientist on shift EXT 24305/24041.
Factors affecting result:
Patient age – Testing not appropriate for patients under 6 month. Please refer to patient’s Newborn screening result if confirmation of sickle status required.Post transfusion – Testing not appropriate if patient is post transfusion. This may give a false negative result. Discuss with laboratory if clinical concern.Testing should not be completed on clotted sample or haemolysed sample. A repeat sample will be requested.