URINE METABOLIC DISORDERS (Branched Chain Amino Acid, Trypthopan, Cystine Disorders)

Question 1

What is the most common IEM in the Philippines, characterized by the absence of branched-chain a-keto acid dehydrogenase (BCKD)?

Answer 1

MSUD

Question 2

What ketoacids are increased in MSUD?

LIV

Answer 2

Leucine, Isoleucine, Valine

Question 3

What is the urine odor associated with MSUD?

Answer 3

Caramelized sugar, Maple syrup, Curry

Question 4

What is sensitive and specific for MSUD?

Answer 4

Alloisoleucine > 5 umol/L

Question 5

What is the positive result for the screening test 2,4-dinitrophenylhydrazine (DNPH) for MSUD?

Answer 5

Yellow turbidity/precipitate

Question 6

What is the confirmatory test for MSUD?

Answer 6

Plasma amino acid testing, Molecular tests

Question 7

What odor is associated with isovaleric acidemia?

Answer 7

Sweaty feet

Question 8

What substance causes the odor in isovaleric acidemia?

Answer 8

Isovalerylglycine

Question 9

What test detects methylmalonic acidemia?

Answer 9

p-Nitroaniline test

Question 10

What is the positive color for methylmalonic acidemia in the p-nitroaniline test?

Answer 10

Emerald green

Question 11

What disorders are associated with tryptophan metabolism?

Answer 11

Indicanuria, Argentaffinoma

Question 12

What is the urine color after air exposure in indicanuria?

Answer 12

Indigo blue

Question 13

What conditions are commonly associated with indicanuria?

Answer 13

Hartnup disease, Intestinal disorders

Question 14

What is the positive result for Obermayer’s test for indicanuria?

Answer 14

Violet color

Question 15

What tumor produces serotonin that is metabolized into 5-HIAA?

Answer 15

Argentaffinoma

Question 16

What is the positive result for the FeCl3 screening test for argentaffinoma?

Answer 16

Blue-green

Question 17

What foods should be avoided 3 days prior to argentaffinoma screening?

Answer 17

Bananas, Pineapples, Tomatoes, Chocolates, Walnuts, Plums, Avocados, Kiwi, Eggplants

Question 18

What medications should be avoided 3 days prior to argentaffinoma screening?

Answer 18

Phenothiazines, Acetanilides

Question 19

What is the urine odor in cystine disorders?

Answer 19

Sulfur

Question 20

What is the renal type of aminoaciduria called?

Answer 20

Cystinuria

Question 21

What amino acids have defective reabsorption in cystinuria (COLA)?

Answer 21

Cystine, Ornithine, Lysine, Arginine

Question 22

What is the positive result for Brand’s modification of Legal’s nitroprusside test for cystinuria?

Answer 22

Red-purple color

Question 23

What reagent is used in Brand’s modification of Legal’s nitroprusside test?

Answer 23

Cyanide nitroprusside

Question 24

What is cystinosis?

Answer 24

An inborn error of metabolism characterized by absence of an enzyme for cystine metabolism

Question 25

What are the types of cystinosis?

Answer 25

Nephropathic cystinosis, Intermediate cystinosis, Ocular cystinosis

Question 26

Where are cystine deposits usually seen in cystinosis?

Answer 26

Bone marrow, Cornea, Lymph nodes, Internal organs

Question 27

What amino acid metabolism defect causes increased homocysteine?

Answer 27

Methionine

Question 28

What enzyme deficiency characterizes homocystinuria?

Answer 28

Cystathione B-synthase

Question 29

What test detects homocystinuria?

Answer 29

Silver nitroprusside test

Question 30

What is the positive color for homocystinuria in the silver nitroprusside test?

Answer 30

Red-purple

Question 31

What color does porphyrin disorders produce in urine?

Answer 31

Red/purple/burgundy

Question 32

What porphyria is associated with colorless urine in lead poisoning?

Answer 32

Colorless porphyria

Question 33

What screening test detects porphyrins D-ALA and PBG?

Answer 33

Ehrlich’s reaction

Question 34

What fluorescence range detects porphyrins?

Answer 34

550-600nm (Violet/Pink/Red fluorescence)

Question 35

What specimen types are used for detecting porphyria?

Answer 35

Urine, Stool, Blood, Bile

Question 36

What enzyme deficiency characterizes acute intermittent porphyria?

Answer 36

Uroporphyrinogen synthase

Question 37

What enzyme deficiency characterizes porphyria cutanea tarda?

Answer 37

Uroporphyrinogen decarboxylase

Question 38

What enzyme deficiency characterizes congenital erythropoietic porphyria?

Answer 38

Uroporphyrinogen cosynthase

Question 39

What enzyme deficiency characterizes variegate porphyria?

Answer 39

Protoporphyrinogen oxidase

Question 40

What enzyme deficiency characterizes erythropoietic protoporphyria?

Answer 40

Ferrochelatase

Question 41

What enzyme does lead poisoning inhibit in porphyria disorders?

Answer 41

ALA synthetase and ferrochelatase

Question 42

What compounds are increased in acute intermittent porphyria?

Answer 42

ALA, PBG

Question 43

What porphyrins are increased in porphyria cutanea tarda and congenital erythropoietic porphyria?

Answer 43

Uroporphyrin

Question 44

What porphyrins are increased in congenital erythropoietic porphyria and variegate porphyria?

Answer 44

Coproporphyrin

Question 45

What porphyrins are increased in erythropoietic protoporphyria and lead poisoning?

Answer 45

Protoporphyrin

Question 46

What porphyrins are increased in acute intermittent porphyria and lead poisoning?

Answer 46

ALA

Question 47

Photosensitivity is common in which porphyrias?

Answer 47

Porphyria cutanea tarda, Congenital erythropoietic porphyria, Variegate porphyria, Erythropoietic protoporphyria

Question 48

Neurologic symptoms are common in which porphyrias?

Answer 48

Lead poisoning, Variegate porphyria, Acute intermittent porphyria

Question 49

What is the treatment for cystine disorders?

Answer 49

D-penicillamine