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CLINICAL MICROSCOPY > Urine Screening for Metabolic Disorders > Flashcards

Urine Screening for Metabolic Disorders Flashcards

1
Q

Disorders resulting from disruption of a normal metabolic pathway that causes increased plasma concentrations of the nonmetabolized substances

A

Overflow disorders

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2
Q

Overflow disorders are frequently associated with

A

Inborn error of metabolism (IEM), or by organ malfunction from disease or toxic reactions

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3
Q

Abnormal accumulations of the renal type caused by malfunctions in the tubular reabsorption mechanism

A

Renal disorders

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4
Q

Gold Standard test for newborn screening

A

Tandem mass spectrophotometry (MS/MS)

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5
Q

The most well-known of the aminoacidurias

A

Phenylketonuria

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6
Q

Urine odor of patient with phenylketonuria

A

Mousy

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7
Q

Enzyme deficient in cases of phenylketonuria

A

Phenylalanine hydroxylase

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8
Q

Urinalysis result of patient with phenylketonuria shows increased amounts of

A

Keto acids, including phenylpyruvate

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9
Q

How does phenylketonuria produce fair complexion in children?

A

Normal conversion of phenylalanine to tyrosine is disrupted; leading to decreased production of tyrosine and its pigmentation metabolite melanin

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10
Q

In phenylketonuria, gene is inherited as an autosomal dominant trait. True or False?

A

False; recessive

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11
Q

How to manage phenylketonuria?

A

Dietary changes that eliminate phenylalanine

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12
Q

Positive result of ferric chloride test for phenylketonuria

A

Permanent blue-green color

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13
Q

Describe the principle and process of guthrie blood test for PKU

A

Principle: same as culture sensitivity testing

  1. Media containing beta-2-thieneylalanine, an inhibitor of Bacillus subtilis, is streaked with the bacteria
  2. Blood impregnated discs placed on the agar; phenylalanine counteracts the inhibitor, and bacteria grow around the disc

NOTE: bacterial growth indicates presence of phenylalanine; patient has PKU
Bacterial growth is due to phenylalanine countering the effect of the beta-2-thienylalanine

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14
Q

In tyrosinemia, the urine may contain excess tyrosine or its degradation products, _____ and _____

A

p-hydroxyphenylpyruvic acid
p-hydroxyphenyllactic acid

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15
Q

Urine odor of patient with tyrosinemia

A

Rancid butter odor

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16
Q

Metabolic classification of tyrosinemia

A

Transitory tyrosinemia
Acquired severe liver disease

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17
Q

Tyrosinemia seen in premature infants, which is caused by underdevelopment of the liver function required to produce the enzymes necessary to complete the tyrosine metabolism

A

Transitory tyrosinemia

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18
Q

Tyrosinemia that produces tyrosyluria resembling that of the transitory newborn and is more serious

A

Acquired severe liver disease

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19
Q

In Transitory tyrosinemia and Acquired severe liver disease, tyrosine and leucine crystals are frequently seen. True or False?

A

False; rarely seen

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20
Q

Hereditary classification of tyrosinemia

A

Type 1 tyrosinemia
Type 2 tyrosinemia
Type 3 tyrosinemia

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21
Q

Deficient enzyme in Type 1 tyrosinemia

A

Fumarylacetoacetate hydrolase (FAH)

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22
Q

Deficient enzyme in Type 2 tyrosinemia

A

Tyrosine aminotransferase

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23
Q

Deficient enzyme in Type 3 tyrosinemia

A

p-hydroxyphenylpyruvic acid dioxygenase

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24
Q

Tyrosinemia with generalized renal tubular disorder and progressive liver failure in infants soon after birth

A

Type 1 tyrosinemia

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25
Q

Tyrosinemia with corneal erosion and lesions on the palms, fingers, and soles of the feet believed to be caused by crystallization of tyrosine in the cells

A

Type 2 tyrosinemia

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26
Q

Tyrosinemia leading to mental retardation if dietary restrictions of phenylalanine and tyrosine are not implemented

A

Type 3 tyrosinemia

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27
Q

Positive result of ferric chloride test for tyrosinemia

A

Transient green color

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28
Q

Positive result of Nitroso-Naphthol Test for Tyrosine

A

Orange-red color

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29
Q

Byproducts of the second metabolic pathway for tyrosine

A

Thyroxine
Epinephrine
Melanin
Protein
Tyrosine sulfate

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30
Q

Responsible for the dark color of hair, skin, and eyes

A

Melanin

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31
Q

Deficient production of melanin leads to

A

Albinism

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32
Q

Elevated urinary melanin indicates

A

Proliferation of the normal melanin-producing cells (melanocytes), producing a malignant melanoma

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33
Q

Describe the production of dark urine due to melanin

A

Tumors (malignant melanoma) secrete a colorless precursor of melanin, 5,6-dihydroxyindole, which oxidizes to melanogen and then to melanin, producing the characteristic dark urine

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34
Q

Positive result of Ferric Chloride Tube Test for melanuria

A

Black /gray precipitate

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35
Q

Positive result of Sodium Nitroprusside Test for melanuria

A

Purple color

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36
Q

Positive result of Ehrlich Test for melanuria

A

Red color

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37
Q

Observed in urine that has darkened after becoming alkaline from standing at room temperature

A

Alkaptonuria

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38
Q

Alkaptonuria also means

A

“Alkali lover”

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39
Q

Third major defect in the phenylalanine-tyrosine pathway

A

Alkaptonuria

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40
Q

Enzyme deficient in cases of alkaptonuria

A

Homogentisic acid oxidase

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41
Q

Deposits of homogentisic acid in the cartilage leads to

A

Arthritis

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42
Q

Positive result of Ferric Chloride Tube Test for alkaptonuria

A

Transient deep blue color

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43
Q

Positive result of Clinitest for alkaptonuria

A

Yellow precipitate

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44
Q

Positive result of Ammonium Hydroxide and Silver Nitrate Test for Homogentisic Acid

A

Black/ darkening color

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45
Q

Quantitation method of homogentisic acid

A

Paper and Thin Layer Chromatography

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46
Q

Branched chain amino acids disorders

A

MSUD
Organic acidemias

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47
Q

Accumulation of one or more of the early amino acid degradation products

A

MSUD

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48
Q

Accumulation of organic acids further down in the amino acid metabolic pathway

A

Organic acidemias

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49
Q

A significant laboratory finding in branched-chain amino acid disorders

A

Ketonuria

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50
Q

Amino acids involved in MSUD

A

Leucine
Isoleucine
Valine

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51
Q

Urine odor of patient with MSUD

A

Caramelized sugar/burnt sugar/curry odor/maple syrup odor

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52
Q

Maple syrup odor of urine is due to

A

Accumulation of keto acids

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53
Q

Positive result of 2,4-Dinitrophenylhydrazine (DNPH) Test for MSUD

A

Yellow precipitate

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54
Q

The three most frequently encountered organic acidemia disorders

A

Isovaleric acidemia
Propionic acidemia
Methylmalonic acidemia

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55
Q

Urine odor of patient with isovaleric acidemia

A

“Sweaty feet”

56
Q

Sweaty feet odor of urine is due to

A

Accumulation of isovalerylglycine

57
Q

Deficient enzyme in cases of isovaleric acidemia

A

Isovaleryl coenzyme A

58
Q

Cause of propionic and methylmalonic acidemias

A

Errors in the metabolic pathway converting isoleucine, valine, threonine, and methionine to succinyl coenzyme A

59
Q

The presence of isovaleric, propionic, and methylmalonic acidemias can be detected by newborn screening programs using

A

MS/MS

60
Q

Positive result of p-Nitroaniline Test for organic acidemias

A

Emerald green color

61
Q

The major concern of the urinalysis laboratory in the metabolism of tryptophan

A

Indicanuria
5-hydroxyindoleacetic acid (5-HIAA)

62
Q

Two usual causes of tryptophan disorders

A

Intestinal infection
Malignant tumors

63
Q

Color of urine exhibiting indicanuria

A

Colorless until oxidized to the dye indigo blue by exposure to air

64
Q

Intestinal disorder causing increased amounts of tryptophan converted to indole

A

Hartnup disease

65
Q

Cause of blue diaper syndrome

A

Hartnup disease

66
Q

Hartnup disease causes Fanconi syndrome. True or False?

A

True

67
Q

Substance given to patients with Hartnup disease

A

Niacin

68
Q

Positive result of Ferric Chloride Test for indicanuria

A

Blue or violet color

69
Q

Serotonin is produced from tryptophan by the

A

Argentaffin cells

70
Q

Serotonin is carried through the body primarily by

A

Platelets

71
Q

Cause of urinary 5-HIAA

A

Carcinoid tumors involving the argentaffin (enterochromaffin) cells producing excess amounts of serotonin

72
Q

Adding nitrous acid and 1-nitroso-2-naphthol to urine that contains 5-HIAA causes the urine to turn

A

Purple to black

73
Q

Normal excretion of 5-HIAA

A

2-8 mg/day

74
Q

Excretion >25 mg 5-HIAA/24 hour indicates

A

Argentaffin cell tumors

75
Q

Patient instruction for 5-HIAA test

A

No bananas, pineapples, tomatoes, phenothiazines, and acetanilids for 72 hours

76
Q

Two distinct disorders of cystine metabolism

A

Cystinuria
Cystinosis

77
Q

Cystine disorder caused by defect in the renal tubular transport of amino acids

A

Cystinuria

78
Q

Cystine disorder caused by inborn error of metabolism

A

Cystinosis

79
Q

Urine odor of people with cystine metabolism disorders

A

Sulfur odor

80
Q

Inherited disorder marked by elevated amounts of the amino acid cystine in the urine

A

Cystinuria

81
Q

Cause of cystinuria

A

Inability of the renal tubules to reabsorb cystine filtered by the glomerulus

82
Q

Two modes of inheritance of Cystinuria

A

Cystine, lysine, arginine, and ornithine are not reabsorbed

Only cystine and lysine are not reabsorbed

83
Q

A chemical screening test for urinary cystine

A

Cyanide-nitroprusside

84
Q

Positive result of Cyanide-nitroprusside test for cystinuria

A

Red-purple color

85
Q

Regarded as a genuine IEM

A

Cystinosis

86
Q

Three variations of cystinosis

A

Nonnephropathic Cystinosis
Infantile Nephropathic Cystinosis
Late-Onset Nephropathic Cystinosis

87
Q

Cystinosis that is relatively benign but may cause some ocular disorders

A

Nonnephropathic Cystinosis

88
Q

Cystinosis with rapid progression to renal failure

A

Infantile Nephropathic Cystinosis

89
Q

Cystinosis gradual progression to total renal failure

A

Late-Onset Nephropathic Cystinosis

90
Q

Cause of cystinosis

A

A defect in the lysosomal membranes prevents the release of cystine into the cellular cytoplasm for metabolism resulting to crystalline deposits of cystine in many areas of the body

91
Q

Remedies to prevent the buildup of cystine in tissues

A

Renal transplants
Cystine-depleting medication

92
Q

Defects in the metabolism of the amino acid methionine, producing an increased amount of homocystine throughout the body

A

Homocystinuria

93
Q

Diet change to alleviate metabolic problems in homocystinuria

A

Exclude foods high in methionine

94
Q

Positive result of Cyanide-nitroprusside test for homocystinuria

A

Red-purple color

95
Q

Positive result of Silver-nitroprusside test for homocystinuria

A

Red-purple color

96
Q

Disorders of porphyrin metabolism are collectively termed

A

“Porphyrias”

97
Q

Three primary porphyrins

A

Uroporphyrin
Coproporphyrin
Protoporphyrin

98
Q

Porphyrin precursors

A

α-aminolevulinic acid [ALA] and porphobilinogen

99
Q

The solubility of the porphyrin compounds varies with their structure. True or False?

A

True

100
Q

Porphyrin that is most soluble and readily appear in the urine

A

Uroporphyrin

101
Q

Coproporphyrin is less soluble but is found in the urine, whereas protoporphyrin is not seen in the urine. True or False?

A

True

102
Q

Method to detect coproporphyrin and protoporphyrin

A

Fecal analysis

Bile is a more acceptable specimen to avoid false-positive

103
Q

An indication of the possible presence of porphyrinuria

A

Red or port wine color of urine after exposure to air

103
Q

Porphyria may also exhibit red discoloration of an infant’s diapers; and staining of the teeth. True or False?

A

True

104
Q

Test used only for the detection of ALA and porphobilinogen

A

Ehrlich reaction

105
Q

Test used for the other porphyrins

A

Fluorescent technique

106
Q

Positive result of Fluorescent technique for porphyrins

A

Violet, pink, or red fluorescence

107
Q

Negative result of Fluorescent technique for porphyrins

A

Faint blue fluorescence

108
Q

Test that rules out porphobilinogen and ALA

A

Fluorescent technique

109
Q

Test for the differentiation between the presence of urobilinogen and porphobilinogen

A

Watson-Schwartz Test

110
Q

Testing for the presence of porphobilinogen

A

Hoesch test

111
Q

Common porphyrias

A

Acute intermittent porphyria
Porphyria cutanea tarda
Congenital erythropoietic porphyria
Variegate porphyria
Erythropoietic protoporphyria
Lead poisoning

112
Q

Products most frequently found in the urine of patients with mucopolysaccharide disorders

A

Dermatan sulfate
Keratan sulfate
Heparan sulfate

113
Q

Mucopolysacchariddoses resulting to abnormal skeletal structure, severe mental retardation, and corneal damage

A

Hurler Syndrome

114
Q

Mucopolysacchariddoses resulting to abnormal skeletal structure, severe mental retardation, inherited as a sex-linked recessive, rare in females

A

Hunter Syndrome

115
Q

Mucopolysacchariddoses in which the only abnormality is mental retardation

A

Sanfilippo Syndrome

116
Q

Most promising treatments for mucopolysaccharide disorders

A

Bone marrow transplants
Gene replacement therapy

117
Q

Positive result of Acid-albumin and Cetyltrimethylammonium Bromide (CTAB) Turbidity Tests for mucopolysaccharide disorders

A

Thick, white turbidity formation

118
Q

Reading time of Acid-albumin test

A

30 minutes

119
Q

Reading time of CTAB test

A

5 minutes

120
Q

Positive result of Metachromatic Staining Spot Tests for mucopolysaccharide disorders

A

Blue spot that cannot be washed away with dilute acidified methanol

121
Q

Lesch-Nyhan disease is caused by

A

Disorder of purine metabolism

122
Q

Lesch-Nyhan disease is characterized by

A

Massive excretion of urinary uric acid crystals

123
Q

Deficient enzyme in cases of Lesch-Nyhan disease

A

Hypoxanthine guanine phosphoribosyltransferase

124
Q

The first sign of this disease is often uric acid crystals resembling orange sand in diapers

A

Lesch-Nyhan disease

125
Q

The presence of increased urinary sugar

A

Melituria

126
Q

Most meliturias cause no disturbance to body metabolism except for _____

A

Galactosuria

127
Q

Inability to properly metabolize galactose to glucose

A

Galactosuria

128
Q

Galactosuria can be caused by a deficiency in any of three enzymes:

A

Galactose-1-phosphate uridyltransferase (GALT)
Galactokinase
UDP-galactose-4-epimerase

129
Q

Deficient enzyme in cases of galactosuria that causes severe, possibly fatal symptoms associated with galactosemia

A

Galactose-1-phosphate uridyltransferase (GALT)

130
Q

Deficient enzyme in cases of galactosuria that causes cataracts in adulthood

A

Galactokinase

131
Q

Deficient enzyme in cases of galactosuria that may be asymptomatic or produce mild symptoms

A

UDP-galactose-4-epimerase

132
Q

Diet change for the management of galactosuria

A

Removal of lactose

133
Q

Carbohydrate disorder seen during pregnancy and lactation

A

Lactosuria

134
Q

Carbohydrate disorder associated with parenteral feeding

A

Fructosuria

135
Q

Carbohydrate disorder associated ingestion of large amounts of fruit

A

Pentosuria

CLINICAL MICROSCOPY (20 decks)

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