Dear Friends
My learned old friend Rick makes an honest point. I just wonder how useful is it in the day to day practice of medicine?
Briefly, in the day to day everyday practice of medicine, do we actually need to know the intracellular magnesium level? Is there one specific condition where one or a set of measurements of the intracellular magnesium level specifically clinches the diagnosis or directly influences management of a patient, and where that diagnosis or management decision could else not be made?
Some of the causes of magnesium deficiency are predictable. For example cisplatin toxicity is managed by pre- and posthydration including potassium and magnesium supplements.
There is a list of causes of hypomagnesaemia which can be learned for finals and membership, including the triad of low magnesium, potassium and calcium going together.
The treatment will be to give magnesium supplementation, either i-v or orally. Of course, hypermagnesaemia can also be toxic. However, it would seem that the situation is akin to finding a diabetic unconscious: you give them some glucose, not insulin, unless you have a blood glucose result.
Likewise, in glucose homeostasis, it could be argued that it is the intracellular glucose level which matters, not least that of the brain. Yet, we manage diabetes by monitoring the blood glucose level and HbA1c levels.
Indeed, hypokalaemia presents the same problem, and we still manage that by squinting at the serum potassium results.
Kind regards
-----Original Message-----
From: Rick Jones [mailto:[log in to unmask]]
Sent: 27 July 2000 18:24
To: [log in to unmask]
Subject: Re: Low magnesium - what does it mean
How low does magnesium go without obvious clinical problems?
This is the wrong question since the effects of Mg deficiency are
manifestations of intracellular deficiency - esp. in relation to high
energy phosphate reactions. Serum Mg is a very poor marker of
intracellular levels. Nucleated cell levels (eg White cells) are better
but difficult to measure. Muscle biopsy is relatively good but painful
and logistically difficult!
It may be that biochemistry is the wrong assessment modality.
Spectrometry of ATP/AMP/ADP using MRI or another physical
method (cf tented t waves for k+) could be a better route for
diagnosis. Any good hybrid physicists/biochemists out there with
an answer?
Rick
Dr Rick Jones
Director of Chemical Pathology and Immunology
Institute of Pathology
Tel:(44)-113-233-5677
Fax:(44)-113-233-5672
http://www.acb.org.uk
http://www.yichi.org.uk
http://www.leeds.ac.uk/rdinfo //Winner - Best Health Database HC99
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