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Retired NBME 20 Answers

nbme20/Block 4/Question#43 (reveal difficulty score)
A physician is assigned to a search and ...
Negative nitrogen balance 🔍 / 📺 / 🌳 / 📖
tags: biochem

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 +13  upvote downvote
submitted by guillo12(58)
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Negative nitrogen balance is associated with burns, serious tissue injuries, fevers, hyperthyroidism, wasting diseases, and during periods of fasting. This means that the amount of nitrogen excreted from the body is greater than the amount of nitrogen ingested.

Positive nitrogen balance is associated with periods of growth, hypothyroidism, tissue repair, and pregnancy. This means that the intake of nitrogen into the body is greater than the loss of nitrogen from the body, so there is an increase in the total body pool of protein.

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guillo12  by Wiki +
shakakaka  What is nitrogen retention, anyone can explain +
drdoom  @shakakaka Nitrogen retention is really just the opposite of having to break down nitrogen-rich molecules (amino acids, protein). This is the default state of your body, i.e., when you're well fed and not starving! +1
drdoom  So, nitrogen retention = “positive nitrogen balance” = an anabolic state. Your body only resorts to breaking down nitrogen-rich compounds (animo acids, protein) when preferred fuel sources like carbohydrates and fats are very low. +1
drdoom  ^ This is because conversion of amino acids to energy (ATP) does not yield as many equivalents of ATP as the other fuel sources, because the breakdown of proteins = breakdown of the very structure of the body (“structural integrity”), and because catabolism of proteins and amino acids often results in nitrogen-heavy byproducts like urea and ammonium that cannot be eliminated as easily as CO2 (which exits freely from the lungs). +
drdoom  “animo acids”? lol🤦🏻‍♀️ +1



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submitted by strugglebus(189)
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You have negative Nitrogen balance in starvation (lack of protein) and positive Nitrogen in muscle building states (i.e. children/athletes)

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celeste  Nitrogen Balance = Nitrogen intake - Nitrogen loss +12



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submitted by andremosq(9)
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Nitrogen is a fundamental component of amino acids, which are the molecular building blocks of protein. Therefore, measuring nitrogen inputs and losses can be used to study protein metabolism.[2]

Positive nitrogen balance is associated with periods of growth, hypothyroidism, tissue repair, and pregnancy. This means that the intake of nitrogen into the body is greater than the loss of nitrogen from the body, so there is an increase in the total body pool of protein.

Negative nitrogen balance is associated with burns, serious tissue injuries, fevers, hyperthyroidism, wasting diseases, and during periods of fasting. This means that the amount of nitrogen excreted from the body is greater than the amount of nitrogen ingested.

A negative nitrogen balance can be used as part of a clinical evaluation of malnutrition.

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