metabolic disorders Flashcards
describe difference between cystinosis and cystinuria
-
- cystinuria: renal disorder, inability to reabsorb cystine = excess cystine
- cystinosis: overflow disorder, lysosomal membrane defect causing incomplete cytie metabolism = excess cystine in body that blocks reabsorption
true or false
IEM (inborn error of metabolism) is screened in newborn screening via tandem mass spec
true
list metabolic constituents/conditions detectable by urine color
- homogentisic acid: black
- melanin: black
- indican: blue
- porphyrins: port red
list abnormal metabolic constituents or conditions detected by odor
- PKU: mousy
- MSUD
- Isovaleric academia: sweat eet
- cystinuria: sulfur
- cystinosis: sulfur
- homocystinuria: sulfur
list phenylalanine-tyrosine disorders
- phenylketonuria (PKU)
- tyrosyluria
- alkaptonuria
- melanuria
list branched chain amino acid disorders
- maple syrup urine disease (MSUD)
- organic acidemias
list tryptophan disorders
- indicanuria
- 5-hydroxyindoleactic acid
list cystine disorders
- cysinuria
- cystinosis
- homocystinuria
describe phenylketonuria
- most common
- mousy odor
- increased keto acids
- cannot convert to tyrosine
- no melanin formation (tyrosine derivative)
how is phenylketonuria tested for
- blood sample
- tandem mass spec
- ingestion of milk for 24 hours then test
- bacterial inhibition = Guthrie
list urine screening tests for penylketonuria
- done to monitor knwon PKU
- ferric chloride test: permanent blue/green
describe tyrosyluria
- excess tyrosine
- inherited or metabolic
- transitory most common (premature infant)
- acquired = severe liver disease
list urine testing for tyrosuyluria
- tyrosine and leucine crystals (liver disorder)
- ferric chloride = green fading rapidly
- nitroso-naphthol test = orange-red (non specific)
describe melanuria
- increased urine melanin = dark/black
- overproliferation of melanocytes releasing melanogen ox to melinin
UA screening tests for Melanuria
- ferric chloride: gray or black precipitate
- sodium nitroprusside: red
- Ehrlich: red
describe alkaptonuria
- urine becomes darker andr alkaline left standing
- brown pigments deposited in body
list urinalysis tests for alkaptonuria
- ferric chloride: blue
- clinitest: yellow precipitate
- alkalization: alkali to fresh = dark color
- silver nitrate: added to fresh urine = black
list two major groups of defective metabolism of branched-chain amino acids
- accumulation (early degradation products)
- organic acidemias (further down)
describe maple syrup urine disease
- inborn error of metabolism
- includes leucine, isoleucine and valine
- inability to metabolize keto acids = accumulation
list three amino acids involved in maple syurp urine disease
- leucine
- isoleucine
- valine
UA findings of MSU
- maple syrup smell
- ketone pos
list symptoms of organic acidemias
- metabolic acidosis
- increased serum ammonia
- can thrive but with problems
lst common organic acidemias
- isovaleric acidemia
- propionic acidemia
- methylmalonic acidemia
true or false
there is no UA testing for organic acidemias
true
- only tandem mass spec
describe tryptophan disorders - two increasing excretions
- increased excretion of both indican and 5-HIAA
describe indicanuria
- abnormal intestinal reabsorption
- tryptophan converted to indole then indican
- blue urine on oxidization
what is associated with hartnup disease
indicanurie
- inherited metabolic disease
- no reabsorption of tryptophan
- renal tubule abnormalities
define cystinura
defect in renal tubular transport of amino acids
- renal disorder
define cystinosis
inborn error of metabolism
- overflow disorder
- nonfunctional lysosomal membranes
describe cystinuria
- elevated cystine in urine
- inabiility to reabsorb filtered cystine into blood
- lysine, arginine and ornithine not reabsorbed
- renal disorder
list UA findings of cystinuria and testing
- cystine crystals
- cystine calculi (common in children)
- cyanide nitroprusside test = purple
describe cystinosis
- overflow disorder
- defect in the lysosomal membrane prevents cysteine from being metabolized in the cytoplasm
- Crystal deposits in the body
- crystals cover RTE cells and prevent reabsorption ==> acquired fanocni
define homocystinuria
metabolic defect of methionine producing increased homocysteine
UA tests for homocystinuria
- screening: red cyanide nitroprusside (pos)
- confirmatory: red silver nitroprusside (pos)
list 3 main types of porphyrin
- uroporphyin
- coproporphyrin
- protoporphyrin
list two main precursors of interest in porphyrinuria
ALA and porphobilinogen
distinguishing characteristics of porphyrias
port wine red urine
fluorescence (purple, pink or red)
define glycoaminoglycans
located in connective tissue
- inherited disorder = prevents the breakdown of polysaccharide branches
list type of mucopolysaccharidoses
- hurlers - connective tissue in the face
- hunters
- sanfilippo’s - most common
list testing for mucopolysaccharidoses
- CTAB
- acid-albumin
- metachromatic staining spt test
describe Lesch-Nyhan
- purine metabolism disorder
- uric acid crystals
- orange diaper sand
- goat
define melituria
presence of increased urinary sugar (any sugar)
describe galactosuria
inability to metabolize galactose to glucose
- glucose negative, build up of galactose
- galactosemia
