Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Clinical Nutrition 3 > Inborn Errors of Metabolism > Flashcards

Inborn Errors of Metabolism Flashcards

1
Q

What is the definition of inborn errors of metabolism? (IEM)

A

Gene mutations
which cause the dysregulation in the synthesis of enzymes and coenzymes. This causes the accumulation of toxic metabolites, and the consequential deficiency in essential metabolites.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Why does IEM concern us nutritionally?

A

When there is dysregulation, it will affect the transporters necessary for the metabolism of CHO, lipids and AA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How are most IEM expressed?

A
  • Autosomal recessive

- The parents may not show the phenotype, but they carry the copy of the gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

When does IEM usually present?

A

Can present at any age with a wide range of severity but mostly manifest around the newborn period
-Either early (more common) or later onset

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Clinical signs and symptoms?

A
  • Global

- Affecting nearly every system; including neurological, GI, CV, Endocrine and skeleto-muscular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

General signs and symptoms in IEM ?

A
  • Overwhelming illness in the new-born period
  • Recurrent vomiting
  • Poor growth, failure to thrive
  • Developmental delay and mental retardation
  • Loss of previously acquired skills
  • Cardiomyopathy
  • Neuropsychiatric symptoms
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

When was newborn screening initiated for IEM? What was the result?

A
  • Since the 1960s

- There was a high incidence of mental retardation prior to screening

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What was the first test of IEM in newborns?

A

-Urinary phenyl pyruvic acid for PKU

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How is testing done for IEM? In Canada, how many conditions are screened for?

A
  • Dry blood spots collected 24-48 hours after brith to detect metabolic intermediaries
  • Up to 38 conditions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

In the diagnosis at screening of IEM, what can IEM help differentiate?

A
  • In a differential diagnosis of sepsis, anoxic encephalopathy or toxic ingestion
  • If we treat the symptoms, and there is no response there is likely IEM
  • IEM diagnosis strengthens if typical common laboratory tests fail to determine a definitive diagnosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How can IEM present at diagnosis? When can it occur?

A

As an acute or chronic, recurrent or progressive disease at ANY age
-Can occur even in the context of negative family Hx for a genetic or metabolic disorder

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What may be to blame in cases of neonatal death from undetermined causes?

A

IEM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Which IEMs are autosomal recessive?

A
  • Phenyl-ketonuria (PKU)
  • Methylmalonic Acidemia (MMA)
  • Galactosemia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Absent enzyme in PKU?

A

-Phenylalanine hydroxylase (PAH)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Absent enzyme in MMA?

A

-Methyl malonyl-CoA mutase or cobalamine co-factor deficiency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Absent enzyme in galactosemia?

A

GALT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Mitochondrial disorders genetic type?

A

X linke mtDNA mutations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

When enzymes are absent, what is often affected?

A

Nutritional metabolism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

____ babies are at more risk if they only have one copy of the X gene

A

Males

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

When there are issues with energy metabolism as a consequence of the IEM, what can it be linked to

A

Defects in the mitochondrial DNA which is linked to the mother

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the model for nutritional managements for IEM?

A

1) Restrict the amount of substrate
2) Supplement the product to prevent deficiency
3) Supplement the cofactor to increase residual enzyme activity
4) use adjunct therapies to remove the abnormal metabolites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the dilemma in nutritional therapy in IEM?

A
  • Restriction or one or more components
  • Risk of nutrient deficiencies
  • Supplementation required
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the efficacy of nutritional therapy for IEM?

A

variable

24
Q

How must nutritional therapy be designed in IEM/

A

Specific to the pathway, enzyme, coenzyme or transporter affected

25
Q

What is the MAIN end goal of nutrition therapy for IEM?

A

Support adequate growth

26
Q

How can we achieve appropriate growth in the nutritional management of IEM?

A
  • Provide adequate energy, protein (complete AA profiles), vitamin and mineral intake
  • Reflects the achievement of metabolic balance
27
Q

What is the consequence of inadequate energy intake?

A

Causes an endogenous release of nitrogen and AA from muscles, which can be problematic when they accumulate due to specific enzyme deficiencies

28
Q

What is important to maintain metabolic balance?

A

Monitoring the protein-energy ratio

29
Q

Nutritional intervention for IE of protein metabolsim

A
  • Low-protein or nitrogen free foods
  • Low protein breads and pastas (sometimes GF)
  • Will allow for appropriate energy intake without adding more protein to the food pattern
30
Q

Protein nutritional therapy?

A
  • Ensure that it provides an adequate amount of all essential AA
  • Some AAs are not metabolized as efficiently as whole protein, recommended total protein intakes may be higher for some disorders
31
Q

When is growth limited?

A
  • When there is an AA in the shortest supply in the diet

- Inadequate nitrogen intake

32
Q

In inborn errors of AA and protein metabolism, how can energy needs be met?

A

By increasing percentage of energy from CHO or fats

33
Q

Nutritional therapy in fatty oxidation disorders?

A
  • Other sources, such as protein and CHO must be increased to meet E needs
  • Might be overwhelming considering how energy efficient fats are
34
Q

How should vitamin and mineral needs be met?

A

-Must be met with medical foods or judicious use of supplements

35
Q

(T/F) for certain IE, some vitamins are supplemented much higher than DRI levels

A

T

36
Q

Why do vitamins have an enhancing effect on certain metabolic pathways if supplied in pharmacological doses?

A

-Because they are often cofactors in the affected metabolic pathways

37
Q

What is PKU?

A

PKU results from the deficiency of PAH, which results in elevated phenylalanine levels and consequential tyrosine deficiency

38
Q

What will the excess phenylalanies be shunted to?

A

Increase synthesis in phenylketones

39
Q

Why is tyrosine important?

A
  • Muscle protein synthesis
  • Melanin
  • Neurotransmitters
40
Q

Sources of phenylalanine?

A

-Dietary and endogenous muscle protein break down

41
Q

What is the normal plood Phe? When is Phe 10 times higher in the blood? At what level of Phe does not require an intervention?

A
  • Normal: <120 umol/L
  • Classical PKU presents with 10 times higher blood Phe
  • Phe <360 umol does not require an intervention
42
Q

4 key management strategies in PKU?

A
  • Reduce blood Phe under 360 umol/L by fully restricting all protein sources that contain Phe
  • Add little by little intact protein to cover Phe needs
  • Supplementation with large, neutral AA to compete for PHE transporters
  • If inadequate protein, assess deficiencies
43
Q

Acute management so PKU?

A
  • When blood levels <360 umol/L
  • Use Phe-free formulas
  • OK to reintroduce standard formula or breastmilk in controlled amounts
44
Q

Chronic management sof PKU?

A
  • maintain blood Phe 120-360 umol/L

- Support normal growth and developments while preventing nutrient deficiencies

45
Q

How are most formulas supplemented?

A

-Already supplemented with tyrosine

46
Q

In PKU, what are the requirements?

A

-Phe is lower
(NOT absent)
-Tyrosine is higher
-Energy requirements are more or less the same

47
Q

what is galactosemia?

A

-Deficiency of GALT, which allows the conversion of galactose 1-P to glucose 1-P an UDP galactose

48
Q

What are sources of galactose?

A
  • Dietary lactose
  • Galcititiol
  • Galatonate
49
Q

What is the consequence of lack of glucose 1-P?

A

No downstream substrates to continue into glycolysis

50
Q

What is the consequence fo lack of UDP galactose?

A

-Lack of substrate required for various glycoproteins and galactolipids

51
Q

Consequence of galactosemia?

A
  • Liver damage and jaundice
  • Anorexia
  • May lead to sepsis
  • Fatal if left untreated
52
Q

Nutritional managements in galactosemia?

A

-Restriction of lactose and breastfeeding is contraindicated

53
Q

What explains the damages caused by galactosemia?

A

The unmetabolized milk sugars will build up and damage the liver, eyes, kidney and brain

54
Q

Acute managemet of Galactosemia?

A
  • Soy based medical foods
  • PN may be an option if PO or EN doesnt work
  • Medications must be free of lactoe fillers
55
Q

Chronic management of galactosemia?

A
  • Dairy elimination
  • Breastfeeding is contraindicated
  • Food label reading is important
  • F&V okay due to negligible amounts of Gal
  • Recommended continuous monitoring of Vit D status for bone health
56
Q

Is breastfeeding contraindicated in PKU?

A
  • No

- breastmilk is low in phenylalanine, but mother may have to be mindful and consume less phenyalanine

57
Q

What is contraindicated in galactosemia?

A
  • Milk
  • Casein
  • Butter
  • Cream
  • Organ meats
  • Sherbert
  • Whey
  • Lactalbumin
  • Lactoglobulin
  • Fermented soy products and fermented soy sauce

Clinical Nutrition 3 (30 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions