URINE METABOLIC DISORDERS (Branched Chain Amino Acid, Trypthopan, Cystine Disorders) Flashcards
What is the most common IEM in the Philippines, characterized by the absence of branched-chain a-keto acid dehydrogenase (BCKD)?
MSUD
What ketoacids are increased in MSUD?
LIV
Leucine, Isoleucine, Valine
What is the urine odor associated with MSUD?
Caramelized sugar, Maple syrup, Curry
What is sensitive and specific for MSUD?
Alloisoleucine > 5 umol/L
What is the positive result for the screening test 2,4-dinitrophenylhydrazine (DNPH) for MSUD?
Yellow turbidity/precipitate
What is the confirmatory test for MSUD?
Plasma amino acid testing, Molecular tests
What odor is associated with isovaleric acidemia?
Sweaty feet
What substance causes the odor in isovaleric acidemia?
Isovalerylglycine
What test detects methylmalonic acidemia?
p-Nitroaniline test
What is the positive color for methylmalonic acidemia in the p-nitroaniline test?
Emerald green
What disorders are associated with tryptophan metabolism?
Indicanuria, Argentaffinoma
What is the urine color after air exposure in indicanuria?
Indigo blue
What conditions are commonly associated with indicanuria?
Hartnup disease, Intestinal disorders
What is the positive result for Obermayer’s test for indicanuria?
Violet color
What tumor produces serotonin that is metabolized into 5-HIAA?
Argentaffinoma
What is the positive result for the FeCl3 screening test for argentaffinoma?
Blue-green
What foods should be avoided 3 days prior to argentaffinoma screening?
Bananas, Pineapples, Tomatoes, Chocolates, Walnuts, Plums, Avocados, Kiwi, Eggplants
What medications should be avoided 3 days prior to argentaffinoma screening?
Phenothiazines, Acetanilides
What is the urine odor in cystine disorders?
Sulfur
What is the renal type of aminoaciduria called?
Cystinuria
What amino acids have defective reabsorption in cystinuria (COLA)?
Cystine, Ornithine, Lysine, Arginine
What is the positive result for Brand’s modification of Legal’s nitroprusside test for cystinuria?
Red-purple color
What reagent is used in Brand’s modification of Legal’s nitroprusside test?
Cyanide nitroprusside
What is cystinosis?
An inborn error of metabolism characterized by absence of an enzyme for cystine metabolism
What are the types of cystinosis?
Nephropathic cystinosis, Intermediate cystinosis, Ocular cystinosis
Where are cystine deposits usually seen in cystinosis?
Bone marrow, Cornea, Lymph nodes, Internal organs
What amino acid metabolism defect causes increased homocysteine?
Methionine
What enzyme deficiency characterizes homocystinuria?
Cystathione B-synthase
What test detects homocystinuria?
Silver nitroprusside test
What is the positive color for homocystinuria in the silver nitroprusside test?
Red-purple
What color does porphyrin disorders produce in urine?
Red/purple/burgundy
What porphyria is associated with colorless urine in lead poisoning?
Colorless porphyria
What screening test detects porphyrins D-ALA and PBG?
Ehrlich’s reaction
What fluorescence range detects porphyrins?
550-600nm (Violet/Pink/Red fluorescence)
What specimen types are used for detecting porphyria?
Urine, Stool, Blood, Bile
What enzyme deficiency characterizes acute intermittent porphyria?
Uroporphyrinogen synthase
What enzyme deficiency characterizes porphyria cutanea tarda?
Uroporphyrinogen decarboxylase
What enzyme deficiency characterizes congenital erythropoietic porphyria?
Uroporphyrinogen cosynthase
What enzyme deficiency characterizes variegate porphyria?
Protoporphyrinogen oxidase
What enzyme deficiency characterizes erythropoietic protoporphyria?
Ferrochelatase
What enzyme does lead poisoning inhibit in porphyria disorders?
ALA synthetase and ferrochelatase
What compounds are increased in acute intermittent porphyria?
ALA, PBG
What porphyrins are increased in porphyria cutanea tarda and congenital erythropoietic porphyria?
Uroporphyrin
What porphyrins are increased in congenital erythropoietic porphyria and variegate porphyria?
Coproporphyrin
What porphyrins are increased in erythropoietic protoporphyria and lead poisoning?
Protoporphyrin
What porphyrins are increased in acute intermittent porphyria and lead poisoning?
ALA
Photosensitivity is common in which porphyrias?
Porphyria cutanea tarda, Congenital erythropoietic porphyria, Variegate porphyria, Erythropoietic protoporphyria
Neurologic symptoms are common in which porphyrias?
Lead poisoning, Variegate porphyria, Acute intermittent porphyria
What is the treatment for cystine disorders?
D-penicillamine