URINE SCREENING
FOR METABOLIC
DISORDERS
CHAPTER 9
,OVERFLOW VERSUS RENAL
DISORDERS
• Overflow
• Breakdown in a normal metabolic pathway causing accumulation of
previous metabolite
• Overrides Tm or is not normally reabsorbed
• Inherited lack of specific enzyme for protein,fat, or carbohydrate
metabolism—Inborn Error of Metabolism
• Renal
• Functional defects
,DISORDERS CLASSIFIED BY DEFECT
Inherited Overflow Metabolic Overflow Renal
Phenylketonuria InfantileTyrosinemia Hartnup disease
Tyrosinemia Melanuria Cystinuria
Maple syrup urine disease 5-Hydroxyindole-acetic acid
Organic acidemias Porphyria
Cystinosis
Porphyria
Mucopolysaccharidoses
Galactosemia
Lesch-Nyhan disease
, NEWBORN SCREENING
• Current state-mandated screening for as many as 29 inborn
errors of metabolism
• Urine tests are primarily for follow-up
• Disorders can cause abnormal urinalysis results
• Heel stick blood tests are used for testing
• Performed before infant leaves hospital
• Metabolites appear first in the blood
• Analyze by tandem mass spectrophotometry, MS/MS
• Gene testing is being worked on
FOR METABOLIC
DISORDERS
CHAPTER 9
,OVERFLOW VERSUS RENAL
DISORDERS
• Overflow
• Breakdown in a normal metabolic pathway causing accumulation of
previous metabolite
• Overrides Tm or is not normally reabsorbed
• Inherited lack of specific enzyme for protein,fat, or carbohydrate
metabolism—Inborn Error of Metabolism
• Renal
• Functional defects
,DISORDERS CLASSIFIED BY DEFECT
Inherited Overflow Metabolic Overflow Renal
Phenylketonuria InfantileTyrosinemia Hartnup disease
Tyrosinemia Melanuria Cystinuria
Maple syrup urine disease 5-Hydroxyindole-acetic acid
Organic acidemias Porphyria
Cystinosis
Porphyria
Mucopolysaccharidoses
Galactosemia
Lesch-Nyhan disease
, NEWBORN SCREENING
• Current state-mandated screening for as many as 29 inborn
errors of metabolism
• Urine tests are primarily for follow-up
• Disorders can cause abnormal urinalysis results
• Heel stick blood tests are used for testing
• Performed before infant leaves hospital
• Metabolites appear first in the blood
• Analyze by tandem mass spectrophotometry, MS/MS
• Gene testing is being worked on
