[3] LESSON 8: SCREENING FOR METABOLIC DISORDERS Flashcards
Other name: Overflow
Primary Type
Other name: Renal
Secondary
Deficiency: Enzyme
Primary Type
Deficiency: Congenital defect in AA transport system
Secondary
AA in blood: Increased
Primary Type
Secondary
AA in urine: increased
Primary
Secondary
AA in urine: Decreased
Secondary
: generalized failure in proximal convoluted tubule reabsorption
Fanconi’s Syndrome
: failure to inherit a gene that codes for a particular enzyme
Inborn Error of Metabolism (IEM)
Deficiency in phenylalanine hydroxylase
Phenylketonuria
Mousy odor with increased pyruvic acid
Phenylketonuria
Guthrie Bacterial Inhibition Test
Phenylketonuria
Phenylketonuria Confirmatory test:
Ion exchange HPLC
Rancid butter odor
Tyrosyluria
Nitrosonaphthol: orange red
Tyrosyluria
Tyrosyluria
(-) for a gene that decodes for
Type 1-
Type 2-
Type 3-
Fumarylacetoacetate hydrolase (FAH)
Tyrosine aminotransferase
p-hydroxyphenylpyruvic acid dioxygenase
May also be seen in patients with severe liver disease
Tyrosyluria
Deficiency in homogentisic acid oxidase
Alkaptonuria
Increased homogentisic acid
Alkaptonuria
Melanuria
Color:__________
Urine darkens upon air exposure
Melanuria
Maple syrup urine odor
(a-ketoisovaleric acid, aketoisocaproic acid, aketo-b-methylvaleric acid)
Confirmatory Test: Gas/TLC or Nuclear Magnetic Resonance Spectro
MSUD
Sweaty feet
Isovaleric
Color: indigo blue
Indicanuria
Hartnup disease: renal tubular abnormality
Indicanuria
Sulfur odor
Cystinuria
Cystinosis
Homocystinuria
*calculus formation
Cystinuria
Fanconi’s Syndrome (+ glucose, AA, PO4)
Cystinosis
Defects in methionine metabolism
Homocystinuria
ALA hydratase def porphyria
ALA synthetase
Acute Intermittent porphyria
Uroporphyrinogen synthase
Congenital erythropoietic porphyria
Uroporphyrinogen cosynthase
Hereditary coproporphyria
Coproporphyrinogen oxidase
Porphyria cutanea tarda
Uroporphyrinogen decarboxylase
Variegate porphyria
Protoporphyrinogen oxidase
PORPHYRIA
Specimen:
Urine, stool, blood, bile
Detects d-ALA and porphobilinogen
Ehrlich’s Rxn
Tests for uroporphyrin, coproporphyrin & protoporphyrin: violet/pink/red
Fluorescence at 550-600 nm
CDC-recommended test for Lead Poisoning
FEP
- Affect or override tubular reabsorptive capacity of the nephron or failure to inherit a gene required for normal tubular reabsorption
Hereditary and Metabolic Disorders
: inherited defect in tubular response to ADH or acquired from medications
Nephrogenic Diabetes Insipidus
Testing for many substances is now performed using
Tandem Mass Spectrophotometry (MS/MS)
It is capable of screening infant blood sample for specific substances associated with particular IEMs
Tandem Mass Spectrophotometry (MS/MS)
A. PHENYLALANINE-TYROSINE AMINOACIDURIAS
Phenylketonuria
Tyrosyluria
Alkaptonuria
Melanuria
B. BRANCHED-CHAIN AMINOACIDURIAS
MSUD
ORGANIC ACIDEMIAS
Isovaleric
Propionic
Methylmalonic
C. TRYPTOPHAN AMINOACIDURIA
Indicanuria
5-HIAA
D. CYSTINE AMINOACIDURIA
Cystinuria
Cystinosis
Homocystinuria
PORPHYRIAS
ALA hydratase def porphyria
Acute Intermittent porphyria
Congenital erythropoietic porphyria
Porphyria cutanea tarda
Hereditary coproporphyria
Variegate porphyria
SCREENING TESTS
Ehrlich’s Rxn
Fluorescence at 550-600 nm
FEP
Phenylketonuria FeCl3:
blue green
Phenylketonuria 2,4-DNPH:
yellow
The most well-known of the aminoacidurias which may lead to severe mental retardation.
Phenylketonuria
Inherited/metabolic defect
Tyrosyluria
Tyrosyluria
FeCl3:
transient green
Increased homogentisic acid
Alkaptonuria
Alkaptonuria
FeCl3:
transient deep blue
Alkaptonuria
Clinitest:
yellow ppt
Alkaptonuria
Alkalinization:
darkening
Alkaptonuria
Addition of AgNO3 & NH4OH:
red
Melanoma
Melanuria
Tumors secrete [?] which oxidizes to melanogen then to melanin.
5,6-dihydroxyindole
Melanuria
FeCl3:
gray/black ppt
Melanuria
Na Nitroprusside:
red
Melanuria
Erhlich’s:
red
Failure to inherit gene for oxidative decarboxylation
MSUD
MSUD
2,4-DNPH:
yellow turbidity/ppt
MSUD
FeCl3:
green-gray
Isovaleryl CoA deficiency
Isovaleric
Propionic
Methylmalonic
Error in the metabolic pathway
Isovaleric
Propionic
Methylmalonic
Methylmalonic
p-nitroaniline test:
emerald green
Intestinal disorders- obstruction, bacteria, malabsorption
Indicanuria
Indicanuria
FeCl3:
deep blue/violet
Argentaffin cell tumors
5-HIAA
> 25mg/day
5-HIAA
5-HIAA
Nitrosonaphthol:
purple to black
5-HIAA
FeCl3:
blue-green
Inability of the tubules to reabsorb cystine
Cystinuria
Cystinuria
Cynide-nitroprusside test:
red-purple
Incomplete cystine metabolism
Cystinosis
Cystinosis
Cynide-nitroprusside test:
red-purple
Homocystinuria
Cynide-nitroprusside test:
red-purple
: disorders in porphyrin metabolism
PORPHYRIAS
Coproporphyrinogen oxidase
Hereditary coproporphyria
color reaction of MSUD in FeCl3 test
porphyria deficient in protoporphyrinogen oxidase
deficiency in homogentisic acid oxidase
color of melanuria in Na nitroprusside test
bacterial inhibition test for PKU
color of PKU in 2,4DNPH
odor of urine in isovaleric acidemia
mousy odor
odor associated with tyrosyluria
color of urine in indicanuria
POINTS to PONDER…..
Shortly after arriving for the day shift in the urinalysis lab, a Medtech notices that an undiscarded urine has a black color. The previously completed report indicates the color to be yellow. Is this observation significant? What two reactions might be seen with the FeCL3 test? What FeCl3 reaction would correlate with a positive Clinitest?
PKU, MSUD
Cystinuria, Fanconi’s syndrome
Primary
Secondary
- Affect or override tubular reabsorptive capacity of the nephron or failure to inherit a gene required for normal tubular reabsorption.
Hereditary and Metabolic Disorders
: inherited defect in tubular response to ADH or acquired from medications
Nephrogenic Diabetes Insipidus