M AUBF: METABOLIC DISORDERS

• Overflow disorder Result from the disruption of a normal metabolic pathway that causes increased plasma concentrations of the nonmetabolized substances.
• Renal Disorder IS caused by malfunctions in the tubular reabsorption mechanism.
• Inborn Error of Metabolism: Disruption of enzyme function & failure to inherit the gene to produce a particular enzyme
• Phenylketonuria: most well known of the aminoacidurias
• Phenylketonuria: if undetected, results in severe mental retardation
• Phenylketonuria: Ivan Følling in 1934 (Norway)
• Phenylketonuria: Peculiar mousy odor of urine
• Phenylketonuria: Increased urinary ketoacids + phenylpyruvate due to disruption in the conversion of phenylalanine to tyrosine
• Phenylketonuria: caused by failure to inherit the gene to produce the enzyme phenylalanine hydroxylase
• Phenylalanine Blood Level Test: Increased 2-6 weeks prior to the urinary excretion of phenylpyruvic acid
• Phenylalanine Blood Level Test: Detected as early as 4 hours after birth
• Phenylalanine Blood Level Result: normal results is lowered from 4 mg/dL to 2 mg/dL
• Phenylpyruvic acid Urine Test: based upon the ferric chloride reaction performed by tube test.
• Phenylpyruvic acid Urine Test: permanent blue green color
• Guthrie’s microbial inhibition assay result: Bacterial growth with around the paper disks.
• Guthrie’s microbial inhibition assay: blood from a heel stick is absorbed into filter paper circles.
• Guthrie’s microbial inhibition assay: The blood-impregnated disks are placed on culture media with Bacillus subtilis
• Guthrie’s microbial inhibition assay: If increased phenylalanine levels are present in the blood, it will counteracts the action of beta-2-thienylalanine, an inhibitor of B. subtilis that is present in the media
• Tyrosyluria/Tyrosinemia: Accumulation of excess tyrosine in the plasma (tyrosinemia) producing urinary overflow
• Tyrosyluria/Tyrosinemia: Inherited or metabolic defect
• Tyrosyluria/Tyrosinemia: Urine metabolites: p-hydroxyphenylpyruvic acid p-hydroxyphenyllactic aci d
• Tyrosyluria/Tyrosinemia: urine may contain excess tyrosine
• Tyrosyluria/Tyrosinemia: transitory tyrosinemia is the most common; seen in premature infants
• transitory tyrosinemia - underdevelopment of the liver function to produce enzyme for tyrosine metabolism
• Type 1 Fumarylacetoacetate hydrolase: Produces a generalized renal tubular disorder and progressive liver failure in infants soon after birth
• Type 2 tyrosine aminotransferase: Persons develop corneal erosion and lesions on the palms, fingers, and soles of the feet believed to be caused by crystallization of tyrosine in the cells
• Type 3 p-hydroxyphenylpyruvic acid dioxygenase: result in mental retardation if dietary restrictions of phenylalanine and tyrosine are not implemented
• nitroso-naphthol test (urinary screening test) result: Orange-red color
• nitroso-naphthol test (urinary screening test) reagent:

  • 2.63N nitric acid
  • 21.5% sodium nitrite
  • 1-nitroso-2-naptho
• MS/MS test: used to confirm nitro-naphthol test
• Melanuria: pigment responsible for the dark color of hair, skin, and eyes.
• Melanuria: Deficient production of melanin= albinism
• Melanuria: Increased urinary melanin  darkening of urine after exposure to air
• URINARY MELANIN - indicates the overproliferation of the normal melanin producing cells (melanocytes) producing a malignant melanoma.
• URINARY MELANIN produces 5,6,-hydorxyindole that will oxidize melanogen to melanin.
• Ferric Chloride Tube Test: Oxidation of chromogen
• Ferric Chloride Tube Test result: Gray or black ppt
• Sodium Nitroprusside test: Screening test
• Sodium Nitroprusside test result: red color
• Sodium Nitroprusside test Interference - add glacial Hac (reverts color greenish-black)

  • Acetone
  • Creatinine