RE: Haemolysed blood sample

ebedford — Mon, 20 May 2019 18:33:49 GMT

Thanks. the dog is a Tibetan terrier. The problem is our in house machine doesn't read the potassium properly - it does give a value of we look on the machine menu but the actual result says "haemolysed" so it doesn't seem very accurate.

RE: Haemolysed blood sample

Ian Ramsey — Sun, 19 May 2019 13:30:15 GMT

HI,

I don't have an immediate solution but it would be useful to know the breed as this can be a factor.

You suggested that the haemolysis "keeps affecting the potassium value so is extra awkward. "

The amount of haemolysis required to change the potassium level is quite significant in most dogs as most dogs have low K in their RBC. You can assess the degree of haemolysis by measuring Hb in the plasma (and repeating the PCV as suggested). See abstract from a paper in 2003 (2) that might help you.

Pseudohyperkalaemia can be seen in Akitas, Shar-peis, Shibas, Jindos, other East Asian dog breeds, and occasionally, in mixed-breed dogs that appear to have high potassium erythrocytes and a degree of osmotic fragility These dogs may have mild haematological changes such as increased RDW, low MCHC, microcytosis and increased osmotic fragility with or without mild anaemia. (3)

Hope this helps

Ian

1 Pseudohyperkalemia in Akitas. Degen M et al. J Am Vet Med Assoc. (1987)

2. Comparison of whole blood and plasma potassium concentrations in dogs using the Reflovet system. Trumel C1, Verwaerde P, Rascol A, Braun JP. Vet Clin Pathol. 2003;32(3):140-2.

Abstract

BACKGROUND:

The Reflovet system is designed for chemical analysis of whole blood. However, plasma or serum is recommended for potassium analysis because of possible interference from RBC potassium. Because RBC potassium concentration is low in most canine erythrocytes, however, there should be little or no interference.

OBJECTIVE:

The objective of this study was to compare potassium results obtained in whole blood and in plasma from dogs using the Reflovet system.

METHODS:

Blood samples were collected from 104 dogs into lithium-heparin tubes. The potassium concentration was measured in whole blood, and subsequently the PCV was measured. Samples were centrifuged and the potassium concentration was measured in plasma. Comparisons were made using Deming's regression and Bland-Altman difference plots.

RESULTS:

There was very good correlation between results of potassium measurements in whole blood and plasma (r = 0.93). Potassiumvalues were moderately lower in whole blood: Potassium(blood) = 0.912 x Potassium(plasma)+ 0.119. Hemolysis had a negligible effect on the results, but the difference increased with the PCV value. In more than 90% of samples, the difference between the 2 measurements was <or= 0.3 mmol/L.

CONCLUSION:

There is only a negligible difference in most cases between potassium values in canine plasma and whole blood using the Reflovet system.

3) Apparent pseudohyperkalemia in a Chinese Shar Pei dog. Battison A.Vet Clin Pathol. 2007 Mar; 36(1):89-93.

RE: Haemolysed blood sample

ebedford — Sat, 18 May 2019 20:46:21 GMT

Thanks, will try that.

RE: Haemolysed blood sample

Michael Woodhouse — Sat, 18 May 2019 16:41:29 GMT

Not trying to teach you to suck eggs but have you tried taking an extra 1ml, putting it in a serum gel tube and spinning it after 15 mins? That way you get a better idea of whether this is a sampling or storage artefact. You could even do an immediate PCV.