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Published on: June 11, 2014
Comparison of plasma ammonia results from seven different automated platforms in use throughout Central Australia
1SA Pathology, Women's and Children's Hospital's and Children's Hospital, 72 King William Road, North Adelaide 5006, Australia.
Insights
Plasma ammonia measurements from seven different platforms across central Australia correlate well, even when samples are transported over 3000km. This suggests a potential for a common reference interval for plasma ammonia testing.
Area of Science:
- Clinical Chemistry
- Laboratory Medicine
- Paediatric Metabolic Disorders
Background:
- The Women's and Children's Hospital in Adelaide serves a vast catchment area of 2.5 million km² in South Australia.
- Remote care for children with metabolic disorders relies on plasma ammonia results from distant laboratories.
- Seven distinct platforms are utilized for plasma ammonia measurement across this large region.
Purpose of the Study:
- To correlate plasma ammonia results from seven different measurement platforms used in central Australia.
- To assess the reliability of plasma ammonia testing across geographically dispersed laboratories.
Main Methods:
- Frozen plasma aliquots from EDTA samples were used for the study.
- Samples were transported on dry ice to participating laboratories for correlation.
- Plasma ammonia levels were measured at an agreed date and time after thawing.
Main Results:
- Passing-Bablok regression analysis revealed slopes between 1.00 and 1.10.
- Y-intercepts from the analysis ranged from -10 μmol/L to 1 μmol/L.
- These results indicate good agreement between the different measurement platforms.
Conclusions:
- Plasma ammonia results from various platforms generally compare well, despite challenges in measurement and transport.
- Sample transportation over long distances (up to 3000km) did not significantly impair plasma ammonia result correlation.
- The findings suggest the feasibility of establishing a common reference interval for plasma ammonia measurements.
Introduction:
The clinical catchment area for the Metabolic service at the Women's and Children's Hospital in Adelaide, South Australia, covers nearly 2.5millionkm2. Care of children with metabolic disorders in these remote areas is assisted from Adelaide, and at times, using plasma ammonia results from laboratories up to 3000km away. There are seven different platforms measuring plasma ammonia within this vast clinical catchment area. Hence, a correlation study was conducted to examine the relationship between plasma ammonia results from the seven different platforms in use throughout central Australia.
Design & Method:
Multiple aliquots of plasma from remainder EDTA samples for haematological investigations were frozen. Samples were then dispatched on dry ice to the laboratories being correlated. At an agreed date and time correlation samples were thawed and plasma ammonia measured.
Results:
Passing-Bablok regression analysis showed slopes ranging from 1.00 to 1.10 and y-intercepts ranging from -10μmol/L to 1μmol/L.
Conclusions:
Despite the absence of a reference method or reference material and troublesome pre-analytical effects in ammonia measurement, plasma ammonia results from the different platforms in general compare well. The study also demonstrates that samples for ammonia measurement can be transported over great distances and still correlate well. Furthermore, a common reference interval for plasma ammonia may be a possibility.
