monam84
Forum Senior
Topics: 35
Posts: 135
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A newborn with PKU is started on a strict phenylalanine restricted diet. Which of the following amino acids must be supplied to avoid negative nitrogen balance?
Arginine
isoleucine
lysine
tryptophan
tyrosine
I picked tyrosine, just because I know that is is necessary for prod of catecholamine and melanin, but Im not sure of what "nitrogen balance" means. Thanks.
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| silver
Forum Guru
Topics: 21
Posts: 770
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in PKU phenylalanine is not converted into tyrosine because there is deficiency of phenylalanine hydroxylase, so phenylalanine accumalates and forms phenylketones--->PKU. So tyrosine becomes essential and that is why we have to supply it through diet.
if we didn't it would lead to neg. nitrogen balance, and one of the causes of neg. nitrogen balance is dietary deficiency of essential amino acids.
Nitrogen balance: intake=excreted
Neg. balance: dec. intake, and inc. excretion
Pos.balance: inc. intake, and dec. excretion
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| monam84
Forum Senior
Topics: 35
Posts: 135
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Thank for the explanation silver.
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| lq2006
Forum Elite
Topics: 43
Posts: 382
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tyrosine
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| SmokyWaters
Forum Elite
Topics: 6
Posts: 458
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agree with silver....consult LIPPINCOTT if you want to see the answer
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