Transcript Approach to Inborn Error of Metabolism in a Neonate Filomena Hazel R.

Approach to Inborn Error of
Metabolism in a Neonate
Filomena Hazel R. Villa, MD
PL2
Objectives
• To recognize IEM in a neonate with nonspecific signs and symptoms
• To make use of simple lab tests in the
diagnosis of IEM
• To know the initial management of life
threatening conditions associated with IEM
Signs and Symptoms
• May be gradual
• May be sudden
• May be catastrophic
Signs and Symptoms
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Respiratory
Cardiac
GI
Neurological
Infectious disease
Categories of IEM
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Disorders of:
Amino acids
Carbohydrates
Fatty acid
Lysosomal and peroxisomal function
Mitochondrial
Organic acids
Presentation
• Metabolic acidosis
• Hyperammonemia
• Hypoglycemia
Metabolic acidosis
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pH <7.35
Excess H+
HCO3 deficit
Calculate anion gap
– Na – (Cl + HCO3)
– Normal is 8-16meq/l
Metabolic Acidosis
• If Chloride is increased- HCO3 wasting
• GI or renal disorders
• If Chloride is Normal and
Anion gap is > = 16--- excess acid
production
Metabolic acidosis
• Approach is to give Na HCO3
• If unresponsive to HCO3-- IEM
Hyperammonemia
• Normal ammonia level- < 50 umol/l
• > 200 -- IEM
• If within 24 hours of life; preterm, RD
THAN
• After 24 hours- IEM
Hypoglycemia
• Glucose level helps in the differential
diagnosis
STEPS:
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1. Determine if there is metabolic acidosis
2. Is anion gap >16?
3. Is there hypoglycemia?
4. Is there hyperammonemia?
– Within 24 HOL?
– After 24 HOL?
Copyright ©1998 American Academy of Pediatrics
Organic acidemia
• Healthy NB rapidly ill,
– Ketoacidosis, poor feeding
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Vomiting, dehydration
Hypotonia, lethargy
Tachypnea, seizures
Coma, unusual odors
Organic acidemia
• Labs:
• Urine organic acids
• Ketonuria (in the NB)- pathognomonic of
IEM
• Neutropenia, thrombocytopenia
• +/- hyperammonemia
• Abnormal acylcarnitine
Organic acidemia
• Treatment:
• Stabilize
• Get rid of organic acid intermediates, and
ammonia- hemodialysis
• Carnitine
• After stabilization, may resume oral feeds
• Consult dietitian, and metabolic specialist
Urea cycle disorder
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No acidosis (respiratory alkalosis)
No ketones (unlike organic acidemia)
No hypoglycemia
But with hyperammonemia
Urea cycle disorder
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Treatment:
Remove ammonia
Hydration with D10 + electrolytes
D/C all protein x 24 hours—calories from CHO
and fat
• Na phenylacetate/Na benzoate
• Give arginine
• Protein restriction for life
Urea cycle disorder
• Prognosis: guarded
• Even with Treatment, many will die
• Definitive treatment: liver transplant
Summary
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Metabolic acidosis + hyperammonemia
Request for specific lab studies
Consult metabolic specialist
Initial therapy- stabilize patient!
Long term treatment- based on specific
IEM