Donna,

Welcome to Lactnet; it very well can become an obsession.  I have
constant internet hookup for a home-based business and my e-mail gives
a little bell when mail has arrived.  My 6 year old now says that the
"na-na" (my 2 year old's word) people are writing again whenever the
bell rings.  Anyway ... lactose intolerance...  My early days in
nursing were as a Peds GI nurse.

Lactose is the predominate sugar in human milk.  Lawrence gives a
great overview of the biochemistry of human milk in BREASTFEEDING: A
Guide For the Medical Profession.  Lactose is broken down in the gut
by the enzyme Lactase.  Lactase is made at the tip of the intestinal
villi in the "brush border" of the gut; the delicate fibers of the
innermost lining if you can picture this in your mind.  Without
lactase, lactose cannot be digested properly.  The malabsorption of
lactose produces a hydrogen gas in the gut.  Lactase is present by 24
weeks of gestation and continues to climb through out the last
trimester.  "Prematures rapidly increase their lactase levels given a
lactose challenge, " Lawrence, 1994.

There are two common ways to diagnosing lactose intolerance in kids.
One is with a breath hydrogen: the patients fasts, you collect
baseline breath sample, feed lactose, then collect repeated samples.
As the gut produces too much hydrogen, the lungs try to rid the body
of the substance and you see a characteristic rise.  This is tough to
do in kids of any age, but esp difficult with infants.  The second
involves checking the stool for reducing substances - sugars.  If
lactose is not absorbed, sugar is present in the stool.  This could
also be positive for other sugars, but since lactose is the primary
human milk sugar...

I would be greatly interested in how this turns out.  They may also
look at jejunal biopsies to check the health of the brush border.
Please keep us posted.  I would hate to think of this babe being
denied BM if the lactose intolerance were just the symptom, not the
main problem.