At our hospital a low mag level isn't considered critical until it is <1. While I do not wait for the lab to call w/ my lab levels and I am on top of looking at my results, I do remember (prior to moving to ICU) that I was once caught off guard while floor nursing with an extremely low level. Became super busy and was unable to check labs in a timely manner on my 6 patients. When things settled, I was shocked to find that my pt had a mag level of 1.2 and that I wasn't notified. That is when I found out that it isn't considered critical (requiring notification) unless it is < 1.
I suppose (to answer my own question) it is the same with K+ levels. It isn't considered critical until it is 3.0...yet it is aggressively replaced with lower levels.
My concern is that most often the docs are usually aggressive in replacing even modest low levels of magnesium. I am wondering what the rationale is behind not considering it a critical level until it is < 1? That just seems really really low to me.
I would appreciate your thoughts.
Nov 11, '10
I suspect it has to do with what values the lab looks at as "critical" hospital wide versus what is critical for ICU. I know in my ICU the surgeons like to keep the electrolytes a bit on the cushier side (esp. mag, K, and Ca). The patient population is also post cardiothoracic surgery. For example, Cardiologists on the other hand may not be as aggressive in covering a K of 3.2 as the surgeons are unless there is ectopy etc. (I still request coverage anyway if appropriate).
Nov 12, '10
Yea, we are quick to tx even lower levels of normal for K and Mg. I suppose CT sx pts are more prone to arrhythmias b/c of cardiac irritability after surgery. Not to mention, they usually come out with lots of insulin running (decreased K+), end up on some type of diuretic (decreased K+), receive blood products (decreased Ca)... most other "healthier" sick people in the hospital who have a K+ of 3.5 won't have any ectopy issues, but here... it's like drop below a K of 4.0 or a Mg below 2 and you can expect issues.
Nov 21, '10
I believe Hi-Ho is right about ICU vs. hospital wide lab interpretation. The patients in the ICU are sicker, and therefore less likely to tolerate slight electrolyte imbalances than healthier patients (ie: those in other areas of the hospital). The lab likely does not need to notify the postop lap-choley's nurse with a K of 3.2, whereas the postop CAB with a K of 3.2 would be require pretty quick correction... And it is up to the nurse to recognize it quickly.
I think the ICU is a much more PROactive area than other places in the hospital.These slight lab imbalances are corrected before the patient becomes symptomatic.. Ideally anyways.