Beyond Basics
Factors Influencing Digestive Process In A Patient With SBS
Site of Intestine Removed
The severity of complications following resection of
the small intestine is often determined by what portion is affected. The
bulk of digestion and absorption take place in the duodenum and the first
part of the jejunum. However, the entire jejunum can be removed without
much disability except for lactose intolerance,
because the ileum can compensate for this loss. In contrast, resection
of the ileum results in most of the problems seen in SBS because the ileum
is the specific site of absorption for bile acids and vitamin B12. Fat
malabsorption may also be a major complication of ileal resection because
bile acids are required for absorption of this nutrient. Ileal resection
also greatly decreases the capacity of the small intestine to absorb water
and electrolytes.
The colon can increase its absorption of water following
small intestine resection if it is still present. It can also metabolize
undigested carbohydrates passed along from the small intestine, providing
an additional source of energy for the body. However, the presence of
the colon can also increase the incidence of kidney stones in individuals
with SBS. Kidney stones result from a lack of oxalate absorption. Oxalate
is a type of salt found in food that normally combines with calcium in
the small intestine during digestion, passes through the small intestine
and the colon, and is excreted in the feces. After a resection that involves
the distal ileum, fat absorption is impaired. The unabsorbed fat attaches
to calcium, leaving oxalate unattached as it passes into the colon. Rather
than being excreted, oxalate is absorbed by the colon. When oxalate enters
the circulation, it may cause calcium oxalate crystals in the urine and
result in kidney stone formation.
This information
is provided as a general educational service
and is not intended to recommend any particular treatment plan
or to replace the advice of physicians. It is important that patients
seek and rely on the advice of a healthcare professional
about their individual medical conditions.
