Urine Screening for Metabolic Disorders

Question 1

T/F: Many of the abnormal results obtained in the routine urinalysis are related to metabolic disorders rather than renal disease

Answer 1

True

Question 2

Most well known of the aminoacidurias

Answer 2

Phenylketonuria

*If undetected, will result in severe mental retardation

Question 3

Odor of phenylketonuria

Answer 3

Mousy odor

Question 4

Occurs when the normal conversion of phenylalanine to tyrosine is disrupted due to the absence of the enzyme phenylalanine hydroxylase

Answer 4

Phenylketonuria

*Phenylpyruvate is increased

Question 5

The basis for the urine test of phenyl pyruvic acid

Answer 5

Ferric chloride reaction

* The addition of ferric chloride to urine containing phenyl pyruvic acid produces a permanent blue-green color

Question 6

Enumerate the amino acid disorders

Answer 6

1. PKU
2. Tyrosyluria
3. Alkaptonuria
4. Melanuria
5. Maple syrup urine disease
6. Organic acidemias
7. Indicanuria
8. Cystinuria
9. Cystinosis

Question 7

Three types of tyrosyluria and their deficient enzymes

Answer 7

Type 1 - fumarylacetoacetate hydrolase (FAH)
Type 2- Tyrosine aminotransferase
Type 3- p-hydroxyphenylpyruvic acid dioxygenase

Question 8

T/F:

Increased melanin in urine darkens the urine after the urine is exposed to air

Answer 8

True

Question 9

Precursor of melanin which oxidizes melanogen to melanin (responsible for the darkening of urine)

Answer 9

5,6-dihydroxyindole

Question 10

Inborn error of metabolism wherein homogentisic acid accumulates in the blood, tissues, and urine

Answer 10

Alkaptonuria

Question 11

Observed by Garrod, urine from patients with this condition darkened after becoming alkaline from standing at room temperature

Answer 11

Alkaptonuria

“Alkali lover”

Question 12

Observations in diapers of patients with alkaptonuria

Answer 12

Black/brown-stained cloth diapers / Reddish-stained disposable diapers

Question 13

Tests used for Alkaptonuria

Answer 13

1. Ferric chloride test (transient blue color)
2. Clinitest (yellow precipitate)
3. Addition of alkali (darkening of color)
4. Silver nitrate test (black color)
   * All of them reacts with homogentisic acid

Question 14

A significant laboratory finding in branched-chain amino acid disorders

Answer 14

Ketonuria in newborns

Question 15

Amino acids involved in Maple Syrup Disease

Answer 15

LIV
Leucine
Isoleucine
Valine

Question 16

Urine screening test for Maple Syrup disease

Answer 16

2,4-dinitropheylhydrazine

Question 17

Responsible for the sweet smell in MSUD

Answer 17

Accumulation of ketones in urine

Question 18

Odor in isovaleric acidemia

Answer 18

Sweaty-feet

* Due to the accumulation of isovaleryglycine

Question 19

The major concern of the urinalysis laboratory in the metabolism of tryptophan is the increased urinary excretion of the metabolites _ and _

Answer 19

Indole and 5-hydroxyindoleacetic acid (5-HIAA)

Question 20

A rare disease wherein increased amount of tryptophan are converted to indole

Answer 20

Hartnup disease

*Exhibits indicanuria

Question 21

Also known as the “blue diaper syndrome”

Answer 21

Hartnup disease

Question 22

Elevated cystine in urine

Answer 22

Cystinuria

Question 23

Screening test for urinary cystine

Answer 23

Cyanide nitroprusside

Question 24

Positive color of cystine in cyanide nitroprusside test

Answer 24

red-purple

Question 25

Cystinuria vs Cystinosis

Answer 25

Cystinuria : Problem with the reabsorption of cystine
Cystinosis: Defect in the lysosomal membranes prevents the release of cystine for metabolism and incomplete metabolism of cystine results to crystalline deposits

Question 26

Result to the defect in the metabolism of methionine

Answer 26

Homocystinuria

Question 27

An additional screening test for homocystinuria

Answer 27

Silver-nitroprusside test
* Homocystinuria also shows a (+) reaction in cyanide nitroprusside test (same with urinary cystine) but in silver-nitroprusside test, only homocystinuria will yield a + result

Question 28

Porphyrin that is not seen in the urine

Answer 28

Protoporphyrin

Question 29

Most soluble porphyrins

Answer 29

A-aminolevulinic acid (ALA), porphobilinogen and uroporphyrin

Question 30

CDC recommends analysis of whole blood for the presence of free erythrocyte protoporphyrin as a screening test for _

Answer 30

lead poisoning

Question 31

Disorder of porphyrin metabolism

Answer 31

Porphyrias

Question 32

Indication of probable porphyria in urine

Answer 32

Red / Portwine color of urine after exposure to air

Question 33

Screening tests for porphyrinuria

Answer 33

Ehrlich reaction & Fluorescence under UV light in the 550-600 nm range
*Detects ALA and porphobilinogen

Question 34

Test for differentiation of urobilinogen and porphobilinogen

Answer 34

Watson-Schwartz

Question 35

A component in the Ehrlich test that converts ALA to porphobilinogen

Answer 35

Acetyl acetone

Question 36

T/F: The fluorescence method can distinguish amongst uroporphyrin, coproporphyrin and protoporphyrin and it rules out porphobilinogen and ALA

Answer 36

False. It cannot distinguish but it can rule out porphobilinogen and ALA

Question 37

Common types of mucopolysaccharidoses

Answer 37

1. Hunter syndrome
2. Hurler syndrome
3. Sanfilippo syndrome

Question 38

Disorder in purine metabolism that exhibits massive excretion of urinary uric acid crystals

Answer 38

Lesch-Nyhan syndrome

* Failure to inherit the gene hypoxanthine-guanine phosphoribosyltransferase

Question 39

Characteristic finding of Lesch-Nyhan syndrome in babies

Answer 39

Orange sand in diapers

Question 40

Primary concern in Carbohydrate disorders

Answer 40

Galactosuria

• pentosuria- ingestion of large amounts of fruit
• lactosuria - seen in pregnant mothers
• fructosuria - associated with parenteral feeding