9. Metabolic Disorders Flashcards
phenylalanine-tyrosine disorders (4)
Phenylketonuria
Tyrosyluria
Melanuria
Alkaptonuria
branched chain amino acid disorders
Maple syrup urine disease
Organic acidemias
tryptophan disorders
Indicanuria
5-HIAA
cystine disorders
Cystinuria
Cystinosis
Homocystinuria
mucopolysaccharide disorders
Hurler syndrome
Hunter syndrome
Sanfilippo syndrome
purine disorder
Lesch-Nyhan disease
carbohydrate disorders
Pentosuria
Galactosuria
Lactosuria
Fructosuria
2 types of disorders causing abnormal metabolic substances in urine
overflow
renal
2 renal metabolic disorders
Hartnup disease
cystinuria
state-mandated method used to screen newborns for metabolic disorders
tandem mass spectrophotometry (MS/MS)
primary vs secondary aminoacidurias
primary: enzyme defect in AA pathway
secondary: renal tubule transport defect
1 out of 10,000 to 20,000 births
PKU
failure to inherit gene for phenylalanine hydroxylase
function of enzyme
PKU
phenylalanine –> tyrosine
mousy odor
PKU
↓ skin pigmentation
PKU (tyrosine not available for conversion to melanin)
albinism
PKU dietary restrictions
phenylalanine (milk)
aspartame
2 tests for PKU
ferric chloride test (monitors dietary control)
phenylpyruvic acid test
tyrosine or leucine crystals
tyrosyluria
underdevelopment of liver function needed to make enzymes necessary for complete metabolism
tyrosyluria
lack of fumarylacetoacetate acid hydrolase
tyrosyluria type 1
lack of tyrosine aminotransferase
tyrosyluria type 2
erosion and lesions of palms, fingers, soles
tyrosyluria type 2
lack of ρ-hydroxyphenylpyruvic acid dioxygenase
tyrosyluria type 3
test for tyrosyluria
nitroso-naphthol test
can be metabolic products of tyrosine
melanin
thyroxine
epinephrine
tyrosine sulfate
2 types of melanuria
malignant melanoma
albinism
black urine
melanuria
alkaptonuria (after standing at room temp)
black stained cloth diapers, red stained disposable diapers
alkaptonuria
arthritis with brown pigment deposits, especially ears
alkaptonuria
lack of homogentisic acid oxidase
alkaptonuria
tests for alkaptonuria
ferric chloride
clinitest
add alkali to fresh urine
chromatography
silver nitrate
present with ketonuria in the newborn
branched chain amino acid disorders
lack of enzyme needed to decarboxylate 3 keto acids
MSUD
MSUD causes —– and —– to accumulate in blood/urine
branched chain AAs
corresponding keto acids
failure to thrive after 1 week
must be detected by 11th day
MSUD
ketones +, glucose =
MSUD
without tx, MSUD leads to…
brain damage
death w/i months
test for MSUD
2,4-dinitrophenylhydrazine (DNPH) test
yellow turbidity/precipitate test
MSUD
3 organic acidemias
- isovaleric acidemia
- propionic acidemia
- methylmalonic acidemia
sweaty feet odor
isovaleric acidemia
lack of isovareyl coA, leading to accumulation of isovalerylglycine
isovaleric acidemia
normal tryptophan pathway
tryptophan –> indole –> feces
argentaffin cell carcinoma
↑↑serotonin
5-hydroxyindoleacetic acid
affects intestinal absorption and tubular reabsorption; generalized aminoaciduria
Hartnup disease
causes of indicanuria
obstruction
abnormal bacteria
malabsorption
Hartnup disease
abnormal tryptophan pathway
tryptophan –> indole –> indican –> urine (indigo blue)
blue diaper syndrome
indicanuria/Hartnup
Pellagra rash
indicanuria
dietary supplement for those with Hartnup
niacin
indicanuria test
acidic ferric chloride test
tests for 5-HIAA
nitrous acid + 1-nitroso-2-naphthol test
plasma test
5-HIAA test false positives
bananas, pineapples, tomatoes (serotonin)
inability to reabsorb cystine
cystinuria
COAL in urine rules out…
IEM
renal calculi in children
COAL
cystinuria
sulfur smell
cystinuria, cystinosis
cyanide-nitroprusside test
for cystine disorders
defect in lysosomal membrane prevents release of…
cystine
cystinosis
cystinosis deposits build up where?
cornea
bone marrow
lymph nodes
internal organs
3 types of cystinosis
- infantile (nephropathic)
- late onset (nephropathic)
- nonnephropathic
cystine-depleting medications
cystinosis
defect in metabolism of methionine
homocystinuria
failure to thrive, cataracts, thromboembolism
homocystinuria
test for homocystinuria
cyanine-nitroprusside
silver-nitroprusside (specific)
——– forms of porphyrins are dark red/purple and fluoresce
oxidative
porphyrins from most to least water soluble
- porphobilinogen; ALA; uroporphyrin (urine)
- coproporphyrin (urine, feces)
- protoporphyrin (feces)
disorders of porphyrin metabolism
porphyrias
2 types of porphyria symptoms
neurological
photosensitivity
burning sensation with exposure to light
porphyria
lead poisoning
porphyrias
tests for porphyrias
Ehrlich test (Watson Schwartz, Hoesch)
UV light
fecal/bile analysis
blood (CDC recommended)
porphyrias
photosensitivity only (3)
cutanea tarda
congenital erythropoietic
erythropoietic
porphyrias
neurological sx only (2)
acute intermittent
lead poisoning
porphyrias
both neurologic and photosensitivity (1)
variegate
compounds located in connective tissue
mucopolysaccharides
accumulation of incomplete portions of large compounds
mucopolysaccharide disorders
abnormal skeletal structure, accumulation in cornea
Hurler syndrome
abnormal skeletal structure, usually in males
Hunter syndrome
bone marrow transplant
gene replacement
mucopolysaccharide disorders
tests for mucopolysaccharide disorders
acid-albumin turbidity
CTAB test
metachromatic staining
mostly in males
sex linked recessive
Hunter syndrome
Lesch-Nyhan disease
lack of hypoxanthine guanine
lesch-nyhan disease
cannot break down uric acid
mass excretion in urine
sandy diaper
lesch-nyhan disease
self-destruction
lesch-nyhan disease
melituria
increased urinary sugar
excessive ingestion of fruits
pentosuria
lack L-xylulose reductase
pentosuria
3 enzyme deficiencies causing galactosuria
Galactose-1-phosphate uridyl transferase (GALT)
Galactokinase
UDP-galactose-4-epimerase
cataracts in adulthood
galactokinase deficiency
mis-dx of DM
fructosuria