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Year 5 path SW > Chempath 6: Metabolic disorders and screening 2 > Flashcards

Chempath 6: Metabolic disorders and screening 2 Flashcards

1
Q

A neonate presents with cataracts, conjugated bilirubinaemia, hepatomegaly after starting milk feeds.

Most likely metabolic disease ?

A

Galactosaemia

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2
Q

A positive Fehling’s and Benedict’s test in the absence of glucose in the urine suggests …………….

A

Glacatosaemia

These tests detect reducing sugars in the urine.

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3
Q

A baby born in Quebec Canada presents with bloody stool, failure to thrive, jaundice, hepatomegaly and a cabbage like odour.

What is the most likely diagnosis ?

A

Tyrosinaemia (type 1)

treated by restricting tyramine in the diet (soft cheese etc)

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4
Q

A neonate presents with signs of a non-infective encephalopathy, failure to thrive and hyperventilation. The consultant suggests that Protein may be the trigger.

Most likely diagnosis ?

A

Urea cycle disorders

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5
Q

list disorders that count as urea cycle defects

A

lysinuric protein intolerance
hyperornithaemia - hyperammonemia - homocitrullinuria
citrullinaemia type II

all result in a high ammonia
all autosomal recessive
high plasma glutamine

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6
Q

how do you treat ornithine cycle disorders

A 
remove ammonia (using sodium benzoate or sodium phenyl acetate)
reduce ammonia production (by low protein diet)
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7
Q

list key features of urea cycle disorders

A 
vomiting without diarrhoea
respiratory alkalosis 
hyperammonaemia 
neurological encephalopathy 
avoidance or change in diet
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8
Q

causes of hyperammonaemia with metabolic acidosis and a high anion gap

A

organic acidurias
caused by defects within the metabolism of branched chain AA
associated with funny smelling urine (cheesy/ sweaty smell)

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9
Q

presentation of organic acidurias in neonates

A 
unusual odour
lethargy 
feeding problems 
truncal hypotonia/ limb hypertonia 
myoclonic jerks 
hyperammonaemia with metabolic acidosis and high anion gap
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10
Q

presentation of chronic intermittent organic acidurias

A

recurrent episodes of ketosis coma
cerebral abnormalities
Reye syndrome: plasma ammonia, plasma/urine AA, urine organic acids, plasma glucose and lactate

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11
Q

list features of mitochondrial fatty acid beta oxidation disorders

A

cause hypoketotic hypoglycaemia
hepatomegaly and cardiomegaly
investigations = blood ketones, urine organic acids, blood spot acylcarnitine profile

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12
Q

features of carbohydrate disorders

A

cannot break down carbs
galactosaemia
glactose-1-phosphate uridyl transferase (Gal-1-PUT) deficiency is most severe and common form
leads to liver and kidney disease

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13
Q

presentation of carbohydrate disorders

A 
vomiting
diarrhoea
conjugates hyperbilirubinaemia
hepatomegaly 
hypoglycaemia 
sepsis 
bilateral cataracts

inv: urine reducing substances (high galactose levels), red cell Gal-1-PUT

tx - avoid galactose

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14
Q

features of glycogen storage disease type 1 (von Gierke disease)

A

phosphatase deficiency
cannot export G6P and G1P after glucose breakdown
become hypoglycaemic

features: hepatomegaly, nephromegaly, hypoglycaemia, lactic acidosis, neutropenia

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15
Q

features of mitochondrial disorders

A

maternally inherited

defective ATP production - multisystem disease esp affecting organs with high energy requirements

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16
Q

investigations in mitochondrial disorders

A

high lactate
CSF lactate/pyruvate
CK
muscle biopsy

17
Q

features of congenital disorders of glycosylation

A

defect of post-translational protein glycosylation

associated with cardiomyopathy, osteopenia, hepatomegaly, sometimes dysmorphic facial features

18
Q

features of paroxysmal disorders

A

metabolism of long chain fatty acids and biosynthesis of complex phospholipids

neonates: muscular hypotonia, seizures, hepatic dysfunction, mental deficiency
infantile: bony changes

19
Q

features of lysosomal storage disorders

A

defects of lysosomal hydrolyses
accumulation of substrates within organelles - organomegaly
dysmorphia, regression
treat: BM transplant, exogenous enzymes

20
Q

describe what’s been included in the Guthrie screening

A 
1969 - PKU 
1970 - congenital hypothyroidism 
2004 - CF 
2006 - SCD 
2009 - medium chain acylcoa dehydrogenase deficiency
21
Q

2 key features of PKU

A

phenylalanine hydroxylase deficiency

test phenylalanine levels

22
Q

2 key features of congenital hypothyroidism

A

dysgenesis/agenesis of thyroid gland

test TSH levels

23
Q

2 key features of CF

A

mutations of CFTR - viscous secretions - ductal blockages
test: immune reactive trypsin
if positive - DNA mutation detection

24
Q

2 key features of medium chain acylcoa dehydrogenase deficiency

A

fatty acid oxidation disorder

acylcarnitine levels by tandem mass spectrometry

25
Q

define specificity

A

probability in % that someone without the disease will correctly test negative

26
Q

define sensitivity

A

probability in % that someone with the disease will test correctly positive

27
Q

define PPV

A

probability that someone who tests positive actually has the disease

28
Q

define NPV

A

probability that someone who tests negative actually doesn’t have the disease

29
Q

list group 1 metabolic disorders

A

accumulation of toxins…

organic acidameias - high urea, ketones, met acidosis, treat with low protein diet, acetylcarnitise and harm-filtration, funny smells

urea cycle disorders - high ammonia, respiratory alkalosis, vomiting, treat with low protein diet

aminoacidopathies inc PKU - high phenylalanine, blue eyes, retardation

30
Q

list group 2 metabolic disorders

A

reduced energy stores…

glycogen storage disorders - hypoglycaemia, lactic acidosis, hepatomegaly, developmental delay, hepatoblastoma, treat with regular CHO

galactossaemia - increased Gal-1-phosphate levels causing cataracts, hypoglycaemia, neonatal conjugated jaundice, test urine, treat with low lactose/galactose diet

fatty acid oxidation disorders - hypoglycaemia, neonatal conjugated jaundice, low ketones, screen with blood acylcarnitine, test iron organic acids, regular carbs

31
Q

list group 3 metabolic disorders…

A

large molecule synthesis…

peroxisomal disorders - poor feeds, seizures, retinopathy, hepatomegaly, mixed hyperbilirubinaemia

glycosylation disorders - measure serum transferring, lead to retardation and nipple retraction

32
Q

list group 4 metabolic disorders…

A

defects in large molecule metabolism…

lysosomal disorders - slow progressing, neuroregression, hepatosplenomegaly, cardiomyopathy, test urine mucopolysaccharides and WBC enzyme levels

33
Q

list group 5 metabolic disorders…

A

mitochondrial

MELAS, Kearns, Sayre POEMS

involve CNS, muscle, heart, high lactate and CK, muscle biopsy diagnostic

Year 5 path SW (106 decks)

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