Dear Brian,
Thank you very much for drawing attention to the Kroll and Elin paper.
It will be very useful to know, when discussing Mg interpretation in ICU
patients.
We will need to bear in mind, however, some of the limitations which are
apparent from the Kroll & Elin data:-
- the entire series is based on BCG, not BCP albumin assays, which would
diverge more in the more severe APR patients
- among their 90,017 albumin assays, none was below 26 g/l - in contrast,
few of our ICU patients have a serum albumin that high, so we would be
extrapolating well beyond the range of data
- from the N and SEM data at slight hypoalbuminaemia, +/- 2 SD for an
"adjusted Mg" could be at least +/- 0.1 mmol/l
Thanks and best wishes,
Les
> From: Brian Payne <[log in to unmask]>
> Date: Wed, 24 Jul 2002 16:23:38 +0100
> To: Les Culank <[log in to unmask]>
> Cc: [log in to unmask]
> Subject: Re: Severe APR & Magnesium results?
>
> Martin Kroll and Ronald Elin measured magnesium and albumin in more than
> 74,000
> serum specimens from patients (Clin Chem 1985; 31: 244). Presumably their
> population included patients with hypoalbuminaemia as part of the acute phase
> reaction as well as those with chronic hypoalbuminaemia. From the linear
> relationship between magnesium and albumin values below 40 g/L (r=0.991) they
> derived the equation
> Adjusted Mg = total Mg + 0.005(40 - albumin)
> I don't know of any other data.
>
> Brian Payne
>
> Les Culank wrote:
>
>> Dear Mike,
>> Can I raise a different issue from that in my other email, namely the Acute
>> Phase Reaction.
>>
>> Many of our ICU patients have a severe APR with for example CRP over 250,
>> and BCP albumin down in the 8 to 15 region.
>>
>> I've not come across any valid method to assess serum Mg in this context,
>> such as there is for calcium. But I suspect that results of say say 0.6
>> mmol/l, maybe lower, are not necessarily "abnormal".
>>
>> Does anyone know of hard data to interpret serum Mg in these patients?
>>
>> Best wishes,
>>
>> Les
>>
>>> From: [log in to unmask]
>>> Reply-To: [log in to unmask]
>>> Date: Tue, 23 Jul 2002 11:05:11 +0100
>>> To: [log in to unmask]
>>> Subject: Magnesium infusions
>>>
>>> Like many of you I suspect we have observed an exponential rise in
>>> requests or plasma magnesium from our ICU in the last few years.
>>> This started with patients with meningococcal meningitis but now
>>> almost all patients have magnesium results several times a day. I
>>> confess to not having done an extensive literature search but I am
>>> pretty sure that the evidence base for the clinical usefulness of these
>>> measurements is pretty thin. It must be incredibly difficult to sort out
>>> the effects of a low plasma magnesium from all the other problems in
>>> patients on ICU.
>>>
>>> However, now a new phenomenon has arisen which is the treatment of
>>> patients plasma magnesium concentrations in the low normal range
>>> with magnesium infusions leading in at least one case to a
>>> concentration well above the upper reference limit. On talking to one
>>> of my adult colleagues I find we are not alone and this is happening
>>> elsewhere. Can anyone shed any light on this? Are there real dangers
>>> in this apparently cavalier approach to treating biochemistry and not
>>> the patient?
>>>
>>> Mike Addison
>>> .
>>> Dr G.Michael Addison
>>> Royal Manchester Children's Hospital
>>> Pendlebury
>>> Manchester M27 4HA
>>> United Kingdom
>>>
>>> Tel 0161-727-2250(AM)or 0161-220-5342(PM)
>>> FAX 0161-727-2249
>>> Email [log in to unmask]
>>>
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