Brian
We report both the unadjusted and adjusted calcium values, but only give a
range (and therefore flags) for the latter. The unadjusted Ca is needed for
acute pancreatitis scoring using the Glasgow criteria, which Joint British
Guidelines say we should all be using. Also, paediatricians I have worked
with previously are not convinced the adjustment is valid in the newborn and
seem to prefer the raw Ca.
As a general point, I would urge anyone who reports adjusted Ca to check the
validity of their equation using local data. We have needed to alter the
slope and intercept following method changes twice in the last 5 years. And
let's get away from this myth that we are adjusting to an albumin of 40 g/l.
It might make the sums easy, but the concept is false. Our local equation
was at one point adjusting to an apparent albumin of 47, much to the
amazement of medical and lab staff!
Paul Masters
Chesterfield
On Tue, 4 Jun 2002 11:38:00 +0100, Brian Payne <[log in to unmask]>
wrote:
>I am strongly in favour of reporting only the adjusted (corrected) calcium
>concentration. When we reported both it was not unknown to find patients
being
>given vitamin D for a low total calcium when their adjusted value was
normal.
>The reference ranges should be identical (see, for example, Barth JH et al,
Ann
>Clin Biochem 1996; 33: 55-58, last paragraph)
>
>Brian Payne
>
>Frank Alvaro wrote:
>
>> Up until a few weeks ago, we reported total serum calcium (with an
>> associated, age-related reference range) as well as a corrected calcium
>> (without any quoted ref. range). After an approach by some medical staff,
>> we started reporting a reference range for the corrected calcium as well,
>> using an identical range as used for the total calcium.
>>
>> Now, we've been told by other medical staff that highlighting an abnormal
>> total calcium (our computer highlights - on screen and in hard copy - any
>> results outside its ref. range) when the corrected calcium is within
range
>> is non-sensical, as it's the corrected calcium that is clinically
important.
>>
>> All this leads to a few questions:
>>
>> 1. should the quoted reference range for corrected calcium be the same as
>> for total calcium (it seems to me that logically it should be, but there
>> have been some murmers of uncertainty)
>>
>> 2. what abnormal result should we highlight (or not)? Should we overlook
>> (ie don't flag) an abnormal total calcium if the corrected calcium is
>> normal? Or, to take it to the extreme, should we just report the
corrected
>> calcium (and albumin) and leave the measured total calcium unreported?
>>
>> I'd appreciate any comments.
>>
>> Frank Alvaro
>> Senior Hospital Scientist
>> Clinical Chemistry
>> South Western Area Pathology Service
>> Sydney, Australia.
>>
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