cerebral edema (swelling of the tissues of the brain) is
the central concern in managing acute episodes of
MSUD. Excess fluid accumulates in the brain as a
result of the rise in the levels of amino acids and a
loss of electrolyte balance. If untreated, cerebral
edema puts pressure on the parts of the brain that
control breathing and can lead to respiratory failure
and death. It can, however, be treated by doctors
familiar with the management of MSUD.
In extreme cases, MSUD can be treated by liver
transplantation, but dietary therapy is a lower-risk
form of treatment and has equally favorable results.The MSUD special diet
At all stages of the life cycle, the MSUD diet has
the following characteristics:
Careful evaluation of leucine intake on an individual
basis. Leucine is an essential amino acid and cannot
be excluded completely from the diet, even though it
is the most toxic of the BCAAs and is present in
foods in higher concentrations than either valine or
isoleucine. The patient’s tolerance of leucine must be
calculated following measurement of BCAA levels
and remeasured at appropriate intervals during the
first 6 to 12 months of life.
Intake of a protein substitute that provides BCAA-
free amino acids.
Inclusion of a supplement that provides necessary
vitamins, minerals, and trace elements.
Isoleucine and valine supplements, taken as needed.
In some cases the patient’s levels of these two BCAAs
fall below desirable levels, or are too low in reference
to the leucine level. The proportion of amino acids is
important because isoleucine and valine levels drop
more rapidly than leucine. When Levels of ioleucine
and valine are too low, severe rashes may result. Also
leucine may be restricted from further depletion.
Supplementation is necessary at such times to lower
the risk of an acute episode of MSUD.
An adequate intake of calories from one of three
sources: foods naturally low in or free from protein;
specially formulated low-protein foods; and protein-
free energy supplements containing glucose polymers
and fats.
INFANCY.Infants diagnosed with MSUD are
given a special MSUD formula supplemented with
controlled amounts of infant formula.Breastfeeding
is beneficial to some children with MSUD but does not
remove the need for the special formula.
CHILDHOOD TO AGE 10.As children grow older,
they must continue to take a protein substitute alongwith other foods that are weighed and measured at
home to supply the correct amount of leucine. In 2003,
Vitaflo, a company based in the United Kingdom,
introduced a line of protein substitute products and
isoleucine-valine supplements for children and adults
with MSUD.These products can be purchased only
with a doctor’s prescription. The protein substitute
formulation for children from 12 months to 10 years
of age is an unflavored powder containing 8.4 g of
protein equivalent, designed to be mixed with cold
waterto form either a gel or a drink. The formula
includes all necessaryvitamins,minerals, and trace
elements as well as amino acids except for the 3 offend-
ing amino acids, and can be flavored with special
packets in black currant, orange, lemon, raspberry,
or tropical flavors. The product takes less than a
minute to prepare and should be drunk at once; how-
ever, it can be stored in the refrigerator and used
within 24 hours. The child must drink water or a
permitted drink along with the MSUD Gel.
If needed, a packet of valine or isoleucine supple-
ment, which also comes in powder form, is to be mixed
in with the MSUD Gel and flavoring.
Vitaflo also makes a chocolate-flavored low-pro-
tein high-calorie supplement called VitaBite, which
can be eaten like a candy bar, or used in permitted
recipes as a filling for cakes or mixed into Rice Kris-
pies treats.
The child should have leucine levels reevaluated
every 6 to 12 months.
ADOLESCENT AND ADULT.The MSUD protein
substitute for children over the age of 8, teenagers,
and adults contains 15 g of protein equivalent and is
intended to be taken as a low-volume drink. The pow-
der, which contains the daily requirements of amino
acids, vitamins, minerals, and trace elements, is mixed
in a special shaker with 80 mL (about 1/3 cup) of cold
water, shaken well, and drunk immediately along with
water or a permitted beverage. Like the MSUD Gel,
Express can be flavored and mixed with isoleucine or
valine supplements. It can also be stored for no longer
than 24 hours in a refrigerator if necessary.
As with children, adolescent and adult patients
should have their leucine levels measured periodically.
SICK DAY CARE.In order to help prevent a child
from requiring hospitalization during an acute attach
of MSUD, he or she is placed on a diet with an even
lower level than usual of leucine and a higher intake of
special formula. The sick day diet is intended to pro-
vide enough calories and amino acids to meet the
body’s needs and to promote protein synthesis in
order to use up the excess BCAAs in the blood. TheMaple syrup urine disease