Pseudohypokalaemia study
Research type
Research Study
Full title
The association of seasonal pseudohypokalaemia with delay in centrifugation and temperature variation
IRAS ID
205338
Contact name
Sakunthala Jayasinghe
Contact email
Sponsor organisation
Oxford University Hospitals NHS FoundationTrust
Duration of Study in the UK
3 years, 4 months, 31 days
Research summary
Research Summary
GP’s frequently request plasma potassium measurements on specimens from their patients and we see many results we believe to be falsely low when there is a time delay between the sample being taken and analysis. It is thought this may be affected by higher temperatures, and may be more prevalent in summer months. It can lead to patients being falsely diagnosed as having hypokalaemia and can result in unnecessary repeated investigations and hospital admissions.
This project is carried out in 2 stages. Stage 1 involves 2 groups of participants: 35 participants with hypokalaemia recruited either through their GP, or through the renal/metabolic clinic, and 35 participants who will be healthy volunteers recruited through the hospital. In stage 1 we will be taking a blood sample from each participant and analysing this every 2 hours for 8 hours. This will allow us to compare the change of blood potassium values between these 2 groups. Those identified from stage 1 as having a significant drop in potassium after the 8 hour analysis, will be asked to participate in stage 2 of the study which will require a further blood sample. In stage 2 we are carrying out proteomic analysis of the red cell membrane proteins. Stage 2 will only occur if the results from stage 1 provide reason to.
This study is funded by the research and development fund at the department of Biochemistry, John Radcliffe Hospital.
Summary of Results
We report a lot of low potassium values on blood specimens where there is a long delay between the specimen being taken and it being analysed, particularly in hot weather. When these patients come to the hospital for a repeat specimen, the potassium value is often normal. We thought that this might be related to the long period before the specimens are centrifuged to obtain the plasma for analysis.
We measured potassium concentrations in specimens from patients who had been referred with this problem. We stored specimens before centrifuging them for up to 8 hours at room temperature, 4 degrees Celsius and 37 degrees Celsius. We did the same with healthy volunteers who had not been noted to have this problem.
We found that the potassium concentrations dropped in specimens at room temperature in patients compared with healthy volunteers, and the lowest concentration was often found after 8 hours, suggesting that this process may continue for even longer.
We conclude that this is a common problem affecting some patients. Ways to avoid this problem include centrifuging specimens in the GP surgery, and, where this has been done, the problem stops.REC name
East of Scotland Research Ethics Service REC 1
REC reference
16/ES/0126
Date of REC Opinion
22 Sep 2016
REC opinion
Favourable Opinion