Effect of sample type, and timing of assay, on feline blood potassium concentration
Danièlle A Gunn-Moore1, Nicola Reed, Kerry E Simpson
1Royal (Dick) School of Veterinary Studies Hospital for Small Animals, University of Edinburgh, Easter Bush Veterinary Centre, Roslin, Midlothian, Scotland EH25 9RG, UK. danielle.gunn-moore@ed.uk
Insights
Serum samples show higher potassium levels than plasma samples in cats, with potassium increasing over time in both. This finding is crucial for accurate feline health assessments.
Area of Science:
- Veterinary Medicine
- Clinical Pathology
- Feline Health
Background:
- Accurate blood parameter measurement is vital for diagnosing and monitoring feline health conditions.
- Potassium levels can be influenced by sample handling and storage, potentially affecting diagnostic interpretations.
Purpose of the Study:
- To investigate the differences in potassium concentration between serum and plasma in feline blood samples.
- To evaluate the impact of sample ageing on potassium levels in both serum and plasma.
Main Methods:
- Blood samples were collected from 41 cats for various veterinary assessments.
- Samples were processed as either serum or lithium heparin plasma.
- Potassium concentrations were measured at baseline (within 1 hour) and after 48 hours of contact with the cell pellet.
Main Results:
- Serum samples consistently exhibited significantly higher potassium concentrations than plasma samples.
- Potassium levels increased in both serum and plasma samples after 48 hours of ageing.
- The mean difference in basal potassium between serum and plasma was 0.47 mmol/l.
- Elevated potassium levels did not correlate with leukocyte or thrombocyte counts.
Conclusions:
- Sample type (serum vs. plasma) significantly impacts baseline potassium measurements in cats.
- Sample ageing leads to increased potassium concentrations in both serum and plasma.
- These findings highlight the importance of standardized sample handling and processing for accurate feline potassium assessment.
Abstract:
Blood samples were collected from 41 cats presented for pre-anaesthetic assessments, routine geriatric screening, or re-assessment of ongoing chronic medical disorders. Samples were either left to clot or anticoagulated with lithium heparin, then assessed for their potassium concentration within 1h of collection, and again after remaining in contact with their cell pellet for 48 h. There was a significantly higher potassium concentration in the serum samples compared to the plasma samples, both in the basal and 48-h samples (although this difference was most marked in the basal samples). Ageing of both serum and plasma samples also resulted in an increase in the potassium concentration when compared with the basal values for each sample type. The mean difference (basal serum minus basal plasma) in potassium concentration was 0.47 mmol/l. While it is probable that the potassium came from either leukocytes and/or thrombocytes the mean total leukocyte count and the mean thrombocyte count were below the upper limit of the reference intervals for our laboratory and the rise in the potassium level did not appear to be directly related to either of these values.
