2 December 2014 (Tuesday) - Potassium

Here’s a little something that came up whilst working in clinical chemistry a few days ago. I found this set of results:

                             Specimen Results Entry

COBBLEPOT, Oswald                                A+       20/11/2014 u/k
MRS   23/11/1946 67 yrs  F  123456              
Arkham
                  Mr Vladimir Freeze
routine.                              
Specimen No   :  AC619028V               Selected Auth Level : S
--------------------T-------------------T-------------------T-------------------
 NA     136    F000 |ALKP   98     F000 |                   |
 K      8.8    F000 |ALT    6      F000 |                   |
 KBIC   21     F008 |CRP    108    F000 |                   |
 U      13.7   F000 |HINT  ^0.1    F000 |                   |
 CR     131    F000 |IINT  ^6      F000 |                   |
 _GFR   35     F000C|LINT  ^-0.0   F000 |                   |
 PROT   35     F000 |                   |                   |
 ALB    11     F000 |                   |                   |
 GLOB   24     F000 |                   |                   |
 TBIL   8      F000 |                   |                   |
--------------------T-------------------T-------------------T-------------------
LTG comments : EC,GFR,LFT,RKOD


 1 Auth'd   2 Unauth'd   3 Nomin'd   4 Change   5 Reject  6 Options  7 eXit> U
 Disc: CLIN    Sect: CC            David Styles       SRE/APEX    Overtype


That potassium result is high; seriously high and most interestingly JNOT consistent with previous findings


COBBLEPOT, Oswald                                A+       20/11/2014 u/k
MRS   23/11/1946 67 yrs  F  123456              
Arkham

------T-----------------------------------------------------------------------]
  Date|20/11/2014 19/11/2014 18/11/2014 17/11/2014 15/11/2014 14/11/2014      |
  Time|u/k        u/k        16:50      u/k        u/k        01:30           |
  Spec|AC619028V  AC618219L  AC617116S  AC615563X  AC614400T  AC613165N       |
      |BIO        BIO        BIO        BIO        BIO        BIO             |
Test--+-----------------------------------------------------------------------{
NA    |136        137        134        131        127        133             |
K     |8.8        3.9        4.5        4.9        4.8        5.0             |
KBIC  |21                                                                     |
U     |13.7                                                   15.4            |
CR    |131        153        139        141        133        135             |
_GFR  |35         30         33         33         35         34              |
PROT  |35                                                                     |
ALB   |11                                                     13              |
GLOB  |24                                                                     |
TBIL  |8                                                                      |
ALKP  |98                                                                     |
ALT   |6                                                                      |
------T-----------------------------------------------------------------------]
  1 View   2 Graph   3 eXit  X
                            Cursor Down for more                       More >>

                                   
There’s something wrong here. That result’s not right. So a little detective work was in order.

The age of the sample was then checked. The sample was only an hour old.
The nature of the sample was checked. The sample was a SST; not EDTA. An EDTA sample would give a much higher potassium result, but it was something that needed checking.

Perhaps there was EDTA contamination, so calcium levels were analysed. Suspecting EDTA contamination we might expect a very low calcium result.
The result was 1.6... low, but not *THAT* low.


COBBLEPOT, Oswald                                A+       20/11/2014 u/k
MRS   23/11/1946 67 yrs  F  123456              
Arkham
routine.
 Specimen No   :  AC619028V               Selected Auth Level : S
--------------------T-------------------T-------------------T-------------------
 NA     136    F000 |ALKP   98     F000 |                   |
 K      8.8    F000 |ALT    6      F000 |                   |
 KBIC   21     F008 |
CA     1.6    E000 |                   |
 U      13.7   F000 |$CORCA CALUNR E000 |                   |
 CR     131    F000 |CRP    108    F000 |                   |
 _GFR   35     F000C|HINT  ^0.1    F000 |                   |
 PROT   35     F000 |IINT  ^6      F000 |                   |
 ALB    11     F000 |LINT  ^-0.0   F000 |                   |
 GLOB   24     F000 |                   |                   |
 TBIL   8      F000 |                   |                   |
--------------------T-------------------T-------------------T-------------------
LTG comments : EC,GFR,LFT,RKOD


 1 Auth'd   2 Unauth'd   3 Nomin'd   4 Change   5 Reject  6 Options  7 eXit> U
                        


For completeness the potassium assay was repeated on our other analyser.  The result was identical; a genuine result.

This was rather frustrating… the result was suspect. but EDTA contamination should have given a far higher potassium result and a far lower calcium result. Perhaps there was only a little EDTA contamination in this case?


A comment was added to the result:


Note raised potassium ? due to EDTA contamination. Please send repeat
sample for confirmation. Ward (staff nurse) telephoned.


A couple of days later I reviewed the case:


COBBLEPOT, Oswald                                A+       20/11/2014 u/k
MRS   23/11/1946 67 yrs  F  123456              
Arkham

NA    |136       137        138        136        137        134
K     |H         4.3        H          8.8        3.9        4.5
KBIC  |                                21
U     |19.9      19.2       17.5       13.7
CR    |185       162        151        131        153        139
_GFR  |24        28         30         35         30         33
PROT  |44        43         45         35
ALB   |12        13         13         11
GLOB  |32        30         32         24
TBIL  |5         6          6          8
ALKP  |112       121        114        98
ALT   |11        9          7          6




Subsequent results were not consistent with that spurious result. I wonder what happened there.
But the bottom line here is that it’s not all about churning out numbers…. 







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