A Comparison of Haematology results between Greendale and other laboratories

Five samples were sent out to two external veterinary laboratories for Haematology analysis. One might assume that which ever laboratory one sends samples to, the results will always be the same, but this is not always the case. Laboratories do however try to have some sort of correlation, by being involved in external quality assurance programs, but even with this process differences do occur.

Upon comparison with the samples that were sent out to the two laboratories, our data suggested a good correlation for most of the samples, however there was one that gave a very different set of results. The table below shows the two sets of results.

Type of cell External Laboratory Results Greendale Laboratory Results Difference between data (%)
Red blood Cells 6.62 10^12/l 6.64 10^12/l 0.3
Haemoglobin 10.5 g/dl 10.6 g/dl 0.1
Haematocrit/PCV 0.35 l/l 0.31 l/l 11
MCV 52.2 fl 46.7 fl 11
White blood cells 15.6 10^9/l 15.110^9/l 3
Neutrophils 81% 54% 33
Band forms 0% 0% 0
Lymphocytes 11% 21% 47
Monocytes 3% 3% 0
Eosinophils 5% 21% 76
Basophils 0% 1% n/a
Platelet Count 276 10^9/l 254 10^9/l 8

This clearly demonstrates a huge variation between our results and the other laboratories when looking at the white blood cell counts in particular. The sample in question was re-checked, and it gave the same set of data that we had previously reported.

So how can such a large variation occur between two laboratories?

To answer this question, one must first determine what, if any, variations exists in the way the sample is measured in the two laboratories. One big difference between the two laboratories is that, at Greendale we measure the haematology and then do manual counts under a microscope to make sure that the analysers’ data agrees. The third party laboratory however, only measures the sample on the five-part differential analyser, and then looks for morphological changes in the cells, and does not do a manual count.

This clearly demonstrates that relying on the analyser alone and not carrying out a manual check under the microscope could result in the reporting of wrong results and therefore potential mis-diagnosis.