|Carbohydrate Metabolism Disorders|
Carbohydrates are the body's sugar source. Sugars used
to provide energy for the body include glucose ,
sucrose , fructose
among many others. Some sugars need to be broken down, usually by enzymes , before they can be used by the body. If the enzymes needed are not
present (usually due to an inherited disorder), these sugars can build
up and cause problems. The type of problem depends on the sugar involved.
The following is a run down of the main carbohydrate
metabolism disorders :
- Galactosemia . Galactosemia is an
inherited that affects the way the sugar galactose
is broken down, due to the lack of the enzyme galactose-1-phosphate
uridyl transferase. Galactose can be found on its own in food or
is the result of lactose (milk sugar) being broken down into galactose
and glucose. The body uses glucose for energy. In galactosemia, galactose
then builds up and becomes toxic. In reaction to this build up of galactose
the body makes some abnormal chemicals. The build up of galactose and
the other chemicals can cause serious health problems like a swollen
and inflamed liver, kidney failure, ovarian failure in girls, stunted
physical and mental growth, and cataracts in the eyes.
If the condition is not treated there is a 70% chance that the child
could die. About 1 out of 50,000 to 70,000 babies is born without
this enzyme. During pregnancy an
test may detect if the infant has Galactosemia.
Galactosemia is not lactose intolerance. Galactosemia is more
serious because it will cause permanent damage if left untreated.
The treatment for galactosemia is to restrict galactose and lactose
from the diet for life. With a restricted diet the child with galactosemia
may have less severe symptoms. There is no chemical or drug substitute
that can be taken for the missing enzyme. Click
for a list of foods/food labels that indicate the presence of galactose
For more comprehensive information on this topic contact the
for this info.
[ 1 ]
are a group of disorders due to a lack of one or more enzymes needed
to break down glucose into its storage form, glycogen, and back from
glycogen to glucose when the body requires it. Glucose is a critical
source of energy for the brain and is the initial source of energy
for muscles. Thus it must be stored in an easily releasable form.
The liver serves as the glycogen (and therefore glucose) depot for
the brain, while muscles maintain a glycogen supply of their own.
There are at least 10 well recognised varieties of glycogen storage
diseases (list ),
all of which are . In each, glycogen accumulates in the liver
or muscles and sometimes in the kidneys.
[ 2 ]
fructose intolerance (HFI)
. Also known as Fructose-1-Phosphate
, Fructosemia Disorder.
An inherited inability to digest fructose (fruit sugar) or
its precursors (sugar, sorbitol and brown sugar). This is due to a
deficiency of activity of the enzyme fructose-1-phosphate
, resulting in an accumulation of fructose-1-phosphate
in the liver, kidney, and small intestine. People with HFI usually
develop a strong dislike for sweets and fruit. After eating foods
containing fructose, they may experience such symptoms as severe abdominal
pain, vomiting, and hypoglycaemia
blood sugar levels; treated with glucose tablets). Early diagnosis
is important because, while most people who have HFI can lead normal
lives if they adopt a fructose-free diet, the condition can lead to
permanent physical harm, including serious liver and kidney damage,
if left untreated.
[ 3 ]
Also referred to as Essential Fructosuria ,
Hepatic Fructokinase Deficiency , Levulosuria
Disorder . Fructosuria is a very rare, harmless, inherited metabolic
disorder. It is characterised by the excretion of fruit sugar (fructose)
in the urine. Normally, no fructose is excreted in the urine. This condition
is caused by a deficiency of the enzyme fructokinase
in the liver. This enzyme is needed for the synthesis of glycogen (the
body's form of stored energy) from fructose. The presence of fructose
in the blood and urine can sometimes lead to an incorrect diagnosis
of Diabetes Mellitus. About 1 out of 130,000 people in the general population
has fructosuria. No treatment is necessary.
[ 3 ]
A benign inborn error of metabolism due to a defect in the activity
of the enzyme l-xylulose, resulting in high levels of the sugar
l-xylulose in the urine. A harmless condition. Occurs almost
exclusively in Ashkenazim Jews of Polish-Russian extraction.
[ 4 ]
The information in this page is presented in summarised form and has been taken
from the following source(s):
Texas Department of Health Newborn Screening (NBS) Program: http://www.tdh.state.tx.us/newborn/handbook.htm
The Encycloædia Britannica© Online: http://www.britannica.com/
United States National Organization for Rare Disorders, Inc: http://www.rarediseases.org/
4. Online Mendelian Inheritance in Man, OMIM, National
Center for Biotechonology Information:
(def;articles & more)