Plasma ammonia analysis: is transport of samples on ice required?
Research type
Research Study
Full title
Plasma ammonia analysis: is transport of samples on ice required? An investigation in samples from patients with hyperammonaemia.
IRAS ID
315212
Contact name
Ann Bowron
Contact email
Sponsor organisation
Research and Development, Newcastle upon Tyne Hospitals NHS Foundation Trust
Duration of Study in the UK
0 years, 6 months, 2 days
Research summary
Ammonia is highly neurotoxic and increased blood levels cause progressive neurological disease, coma and death. Identification of hyperammonaemia is important to ensure prompt treatment. In vitro amino acid metabolism causes ammonia increases in blood samples at ambient temperature, so samples must be transported to laboratories promptly on ice. Difficulties obtaining ice and delayed transport result in sample rejection, delayed diagnosis of hyperammonaemia and serious neurological damage.
The study aims to investigate stability of ammonia in blood samples stored at ambient temperature taken from patients with high circulating ammonia levels.
Clinically significant ammonia increase will be determined from published data on biological variation and expert opinion of consultants who manage patients with hyperammonaemia, assessed by questionnaire.
Ten patients with high plasma ammonia (> 50 µmol/L) will invited to provide informed consent to give a blood sample. Where the patient lacks capacity, a personal consultee (relative, partner or friend) or medical practitioner will be invited to provide consent on their behalf.
A doctor will take 26 ml blood from the patient and transfer aliquots into sample tubes. Half will be placed on ice and half stored at ambient temperature. One tube from each group will be centrifuged and plasma ammonia analysed immediately (baseline) and the others stored before centrifugation and ammonia analysis every 10 minutes up to 120 minutes.
Plasma amino acids will be measured in the baseline and final samples from each patient to determine whether changes in ammonia can be related to the metabolism of specific amino acids.
Stability of ammonia at ambient temperature will be compared with that on ice. The requirements for storage and transport of blood samples to avoid a clinically significant increase in ammonia will be determined.REC name
London - Bromley Research Ethics Committee
REC reference
22/LO/0628
Date of REC Opinion
17 Oct 2022
REC opinion
Further Information Favourable Opinion