March 1, 2011 (Tuesday) - Dubious Results

A query from a GP. A patient having monthly blood counts was found to be a tad anaemic last Wednesday. Today they are feeling fine, and no clinical symptoms of anaemia. Which is in line with today’s blood count:

DODGY, RESULTS    
DOB  14/10/1066 Sex F Pat No 123456     
Address   YES     

  01/03/2011 23/02/2011 26/01/2011 24/12/2010 22/12/2010      
  Time u/k      10:25      12:00      u/k        u/k      

HB    13.7       8.2        13.3       12.5       12.4
WBC   8.8        8.0        8.6        9.7        10.5 
PLT   309        196        304        424        443 
RBC   4.84       3.37       4.75       4.55       4.46 
HCT   0.440      0.310      0.420      0.390      0.390
MCV   89.9       92.0       88.6       85.9       86.5
MCH   28.3       24.3       28.0       27.5       27.8
MCHC  31.5       26.5       31.6       32.0       32.1
NEUH  6.2        5.5        5.3        6.7        7.4
LYMPH 1.1        1.4        1.7        1.4        1.0
MONO  1.1        0.8        1.2        1.2        1.5
EOS   0.3        0.3        0.3        0.4        0.4

So what was the Hb of 8.2 all about last week? The GP was at a loss to explain what had happened. That's where I came in..

Last week’s results at first sight would indicate blood loss. Or would they? The Hb is reduced over a month, but so is the platelet count. Given the onset of a bleed over the last month, one would expect the platelet count to have risen. And that MCHC looks decidedly fishy.
Bearing in mind the patient’s clinical condition doesn’t match last Wednesday’s results, but is consistent with today’s and that of late January, I suspect that there was something wrong with that sample taken last week. Clotted, insufficient, short-sampled, taken from the wrong patient… the possible explanations for the spurious result are endless. But whatever the cause, the results are clearly not what was expected.

This case illustrates fallacy of taking the results of any blood analysis in isolation. They need to be taken with understanding of what can go wrong in pre- peri- and post analytical systems, in conjunction with the patient’s clinical condition, and in relation to previous and subsequent investigations (if available).

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