From: sbharris@ix.netcom.com(Steven B. Harris)
Newsgroups: sci.med.nursing,sci.med
Subject: Re: very low blood sugar level
Date: 14 Nov 1998 08:44:53 GMT

In <364CB716.3524@lucent.com> Martin Braff <braff@lucent.com> writes:

>Could you comment on the time frame required for brain damage?

Hours.


>Also is heart damage likely from blood sugar this low?


No, never.  The heart by and large doesn't run on sugar.

                             Steve

From: sbharris@ix.netcom.com(Steven B. Harris)
Newsgroups: sci.med.nursing,sci.med
Subject: Re: very low blood sugar level
Date: 15 Nov 1998 03:42:21 GMT

In <364E1525.62670289@tc.umn.edu> aaron <enge0213@tc.umn.edu> writes:

>All cells - even the brain - can also use ketones, intermediates in the
>oxidation of fats.


But there's a limit (about 50%) as to what extent the brain can switch
from sugars to ketones, even in starvation.  Other organs (the heart,
for example) uses almost no sugar under any circumstances.

From: sbharris@ix.netcom.com(Steven B. Harris)
Newsgroups: sci.med.nursing,sci.med
Subject: Re: very low blood sugar level
Date: 16 Nov 1998 01:50:30 GMT

In <72mqdc$6ip@news-central.tiac.net> Beth and Phil
<eshea@tiac*no.SPAM*.net> writes:

>I thought the blood brain/brain barier only allowed glucose across?
>have to dig out my neurophysiology text.   you've got my curiousity
>piqued
>
>Beth

No.  The blood brain barrier passes fats, cholesterol, and many other
lipid soluble things-- else how would neuroactive drugs like
antidepressants and barbiturates work? Also, there are many active
transport systems for things like amino acids to get across the
barrier.  Obviously the brain needs to make proteins and
neurotransmitters.

From: sbharris@ix.netcom.com(Steven B. Harris)
Newsgroups: sci.med.nursing,sci.med
Subject: Re: very low blood sugar level
Date: 16 Nov 1998 01:58:42 GMT

In <72mqea$6ip@news-central.tiac.net> Beth and Phil
<eshea@tiac*no.SPAM*.net> writes:

>Steven B. Harris wrote:
>
>> In <364E1525.62670289@tc.umn.edu> aaron <enge0213@tc.umn.edu> writes:
>>
>> >All cells - even the brain - can also use ketones, intermediates in the
>> >oxidation of fats.
>>
>> But there's a limit (about 50%) as to what extent the brain can switch
>> from sugars to ketones, even in starvation.  Other organs (the heart,
>> for example) uses almost no sugar under any circumstances.
>
>
>then what does the heart use?
>
>
>It was my understanding that muscles ( of which the heart is one)
>require ATP to funtion and the most efficient way to produce ATP from
>ADP is using gulcose in glycolosis.  there are some conductive muscle
>within the heart which work much like nerve cells,  which is a
>completely different ballgame.
>
>Beth


   No.  Glycolysis refers classically only to the splitting of glucose
to 3 carbon units (lactate/pyruvate).  It doesn't require oxygen and
doesn't produce much ATP.  Most ATP is produced oxidatively from
hydrogen/electrons generated in the Krebs cycle, ultimately passed to
molecular oxygen.  The Krebs cycle burns acetyl groups in the form of
acetyl-CoA, remember?

   The heart uses fat.  Specifically fatty acids like palmitate.  They
are broken down to 2-carbon acetyl units (acetyl-CoA), and enter the
Krebs cycle there.  You could live entirely on stored fat for energy
were it not for the brain which still needs some glucose (which can't
be made from fat).

                                          Steve Harris, M.D.

From: sbharris@ix.netcom.com(Steven B. Harris)
Newsgroups: sci.med.nursing,sci.med
Subject: Re: very low blood sugar level
Date: 16 Nov 1998 02:01:24 GMT

In <364edbee.10236565@wingate> Ananasen@hotmail.com (Anna) writes:

>On 15 Nov 1998 03:42:21 GMT, sbharris@ix.netcom.com(Steven B. Harris)
>wrote:
>
>>In <364E1525.62670289@tc.umn.edu> aaron <enge0213@tc.umn.edu> writes:
>>
>>>All cells - even the brain - can also use ketones, intermediates in the
>>>oxidation of fats.
>>
>>
>>But there's a limit (about 50%) as to what extent the brain can switch
>>from sugars to ketones, even in starvation.  Other organs (the heart,
>>for example) uses almost no sugar under any circumstances.
>
>
>And maybe most important, it takes days for the brain to switch to
>using ketonbodies in the first place. Wich excludes them from saving
>the brain in any acute episodes.
>
>Anna


  Yes, but even weeks of starvation and maximal brain switch to ketone
metabolism will not save you from blackout and brain damage if your
blood glucose falls to very low levels.  They key to the danger is that
the changeover is not ever complete, not that it takes too long.

From: sbharris@ix.netcom.com(Steven B. Harris)
Newsgroups: sci.med.nursing,sci.med
Subject: Re: very low blood sugar level
Date: 17 Nov 1998 20:52:58 GMT

In <mark-ya02408000R1611981708360001@news.service.uci.edu>
mark@indy-lv.biomol.uci.edu (Mark Brandt, Ph.D.) writes:

>In article <72o0si$9g8@dfw-ixnews6.ix.netcom.com>,
>sbharris@ix.netcom.com(Steven B. Harris) wrote:
>>
>>    The heart uses fat.  Specifically fatty acids like palmitate. They
>> are broken down to 2-carbon acetyl units (acetyl-CoA), and enter the
>> Krebs cycle there.  You could live entirely on stored fat for energy
>> were it not for the brain which still needs some glucose (which can't
>> be made from fat). ...
>
>and the RBCs, which, lacking mitochondria, are dependent on glycolysis for
>energy.


   Yep.

From: sbharris@ix.netcom.com(Steven B. Harris)
Newsgroups: sci.med.nursing,sci.med
Subject: Re: very low blood sugar level
Date: 30 Dec 1998 09:51:23 GMT

In <%%gi2.1416$zz6.381745@news1.usit.net> "News" <pkeadle@usit.net>
writes:

>In the past week we have had a patient who is an alcoholic. He was found
>by EMS to be totally unresponsive. A fingerstick glucose did not register
>on their glucometer so they drew a red top and then gave him 2 amps of
>D50. He aroused somewhat but remained semi conscious. When they arrived
>at the ER the red top was analysed and showed a glucose of 1 (one) !!


>On the floor q 1 hour fsbs were in the 29-39 range on .45 saline and
>in the 60-90 range on D5 .45.


Comment:
    Somebody sure screwed up not putting him on something containing
D5W to begin with!  If they were doing q 1 hour fasting glucoses, what
were they thinking?  The process was unknown, and their first duty was
to protect the patient from its acute effects.


>No definite cause was determined but the patient developed a seizure
>disorder and was discharged on Hosp. day 7 on Depakote for the
>seizures. Any comments?



    Well, I assume he wasn't a diabetic who forgot to tell you about
it.  But you should have gotten insulin and insulin C-peptide levels
(to tell the difference between natural and injected insulin) anyway.
And had the lab go back and do them from stored alliquots of the first
blood samples you took in the ER.  If you didn't, you're now missing
the same kind of critical info they lacked in the famous criminal von
Bulow case (movie with Jeremy Irons), and as a result you're in the
same quandry.

   Alcohol does impair the liver's ability to make glucose out of
stored glycogen between meals, which is why diabetics are encouraged
to drink alcohol only WITH meals.  Alcoholics are famous for drinking
while starving.  But this doesn't explain a glucose of essentially
zero.  The only time I've ever seen this is with oral diabetic drugs
(the old Diabenese was famous for it) and (relative) overdoses of
insulin.  Alcohol on board might contribute, but not do this by itself.

    In a similar vein, a patient might have an insulinoma, but probably
not a patient who recovers spontaneously and walks out of the hospital
with normal sugars.  So again, a mystery.   Sorry.

                                     Steve Harris, M.D.

From: sbharris@ix.netcom.com(Steven B. Harris)
Newsgroups: sci.med.nursing,sci.med
Subject: Re: very low blood sugar level
Date: 31 Dec 1998 07:40:23 GMT

In <N2Bi2.1543$zz6.417262@news1.usit.net> "News" <pkeadle@usit.net>
writes:

>They did the c-peptide and insulin levels. They also did these on blood
>the EMS did and on blood in the ER. Patients family member denied any
>suicidal ideation. No family memeber or friend was on insulin or any oral
>hypoglycemic med. They also did a cortisol level ; it came back as 6. The
>c-peptide and the insulin levels were unremarkable. No exogenous insulin.
>No sign of insulinoma seen by the endocrinologist. The internal medicine
>teaching staff, the endocrinologist and the neurologist all came to the
>same conclusion, that the alcoholic liver failed to produce glucose.

     I can't come to any other, from what you say.  Good case.
Probably is worth writing up, actually.


> No glucose = brain injury = seizures.


     Perhaps, but here's where I may have something helpful to add.
Old stroke and scar injury is rehabed pretty well, but apparently the
new rerouted circuitry is especially metabolically sensitive, and
there's nothing like a low glucose to make old CNS injury symptoms
return (temporarily).  It all goes away when the glucose returns to
normal, and does NOT necessarily signal new injury.  In fact, usually
it's not.  I've seen frankly hemiplegic people recover completely with
glucose, in hours (they had had old strokes and ONCE been hemiplegic,
but weren't at the time of the metabolic problem).  This guy may well
not need to be on Tegretol or anything else new, so long as his glucose
levels are up.  He may simply have a scar from an old fall injury
(common in alcoholics), or a very small old stroke/scar focus, which
acts up only under hypogycemic stress.

    In addition, there is always the tricky situation of giving glucose
to sometimes thiamine-deficient alcoholics, which can produce a general
neuro stress, which also interacts with old injuries to produce
transient neuro signs that go away when the thiamine finally starts
working.  It's sometimes assumed that the thiamine routinely given to
alcoholics stops this kind of thing.  Wrong.  It helps, but it's no
*guarantee* of immediate protection.  It takes TIME for thiamine to
work, and the metabolic stress of IV glucose is sometimes more
immediate.


>I was mostly distressed that no cerebral testing was done.  No CT, MRI
>etc etc to rule out head injury.  Just because one  malady is present
>that does not mean that a co existing condition could not occur.


   No, it would have been reasonable, and might even have showed
something (some small lesion, or even something like a subdural
hematoma, very common in alcoholics).  But probably something old.  And
there is a good chance that even if it did, there may well still have
been no reason to treat with long term anticonvulsants, given the
history of seizure under severe metabolic brain stress conditions.

    BTW, it takes a surprisingly long time to do really significant
injury to the brain with no glucose.  Usually more than an hour or two.
Insulin alone is responsible for only a minority of the cases, and the
real brain burners were the old long acting oral hypoglycemic agents.
Not that this is what I think you were seeing-- just that I want to
make the point that unless he was on no glucose for a LONG time (like
all night), he probably didn't do that much permanent damage.

>(Incidentally I am a Orthopaedic Nurse Certified.  This is what
>happened when bed control decided a nurse is a nurse and put this very
>sick medical patient on my unit on a weekend!  Any of you Ortho guys
>want to try managing medical for awhile???)


   With seizure, and alcohol withdrawal and glucose monitoring
precautions, multiple tests and antibiotic coverage against aspiration,
this guy would have been a reasonable candidate for an ICU, just from
the nursing care standpoint.  Nobody would have had rational reasons to
argue, unless your ICU was full.   I took care of a similar insulin
overdose case on the medical ward not two weeks ago, but I had a really
good intern and resident, and it WAS a medical floor.  They did you
wrong, no question.

                                        Steve Harris, M.D.