inborn error of metabolism
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To recognize IEM in a neonate with non-specific 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
Individually rare, collectively a significant health problem
Approx 1:5,000 live births.
Disorders of metabolism: Amino acids Carbohydrates Fatty acid Lysosomal and peroxisomal function Mitochondrial Organic acids
May be gradual May be sudden May be catastrophic
Infectious disease
Respiratory Cardiac GI Neurological
Metabolic acidosis
Hyperammonemia
Hypoglycemia
Aminoacidopathies or Galactosemia
Infection
Obtain plasma ammonia
Normal High anion Gap Normal anion gap
Acidosis
Urea Cycle defects Organic acidemias
Metabolic Disorder
High
Obtain blood pH and CO2 Obtain blood pH and CO2
Normal
Poor feeding Vomiting, dehydration, Tachypnea, seizures, Coma
Transient hyperammonemia
of the newborn
No acidosis
Obtain plasma amino acids
Normal or low
Acidosis
CPS deficiency or NAG synthetase
deficiency
Specific amino acid elevation
Obtain urine orotic acid
No specific amino acid elevation
Obtain blood pH and CO2
Obtain plasma citrulline
Normal or elevated
Low
OTC deficiency
HHH syndrome
Argininosuccinic acidemia
ArgininemiaCitrullinemiaOrganic acidemias
Obtain organic acids
High
Copyright ©1998 American Academy of Pediatrics
Can be life threatening event requiring rapid assessment and management.
ABC’s
CBC BloodCx if uncertain
Coags- PT/PTT BSR,RFTs, Ca and LFTs LP- r/o Meningitis, ABG-acidosis NH4 Lactate, Pyruvate , UA-ketones, urine
reducing substances, lactate
Correct hypotension.
NPO, reverse catabolism with D5-D10 1-1.5 x maint.
Correct hypoglycemia.
Correct metabolic acidosis.
Lactulose; Dialysis, if High/toxic NH4 › (nl is <35µmol/L)
Search for and treat precipitants; ie: Infection, dehydration.
Sepsis + ABx if uncertain.
Pyridoxine for neonatal sz. if AED no-response
.
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?
No acidosis (respiratory alkalosis) No ketones (unlike organic acidemia) No hypoglycemia But with hyperammonemia
Treatment: Hydration with D10 + electrolytes D/C all protein x 24 hours—calories from
CHO and fat Remove ammonia Na phenylacetate/Na benzoate Give arginine Peritoneal dialysis if above measure fail Protein restriction for life
Prognosis: guarded Even with Treatment, many will die Definitive treatment: liver transplant
Healthy NB rapidly ill, › Ketoacidosis, poor feeding
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
Treatment: Stabilize Get rid of organic acid intermediates,
and ammonia- dialysis Carnitine After stabilization, may resume oral
feeds Consult dietitian, and metabolic
specialist
**Autosomal recessive inheritance** Examples are MCAD, LCAD, VLCAD Defect in acyl-CoA Dehydrogenase important in
fasting state. KEY features: Acute attack of life-threatening coma with
Hypoglycemia Absence of urine ketones, and reducing substances, +/- mild acidosis, or hyperammonemia, elevated
LFTs, abnl coags. +/-Hepatomegaly-/+ Dx with serum Acylcarnitine Profile or fibroblast
enzyme assay Treat ment: correct hypoglycemia with 10%D/W
and avoid fasting
Metabolic acidosis + hyperammonemia Initial therapy- stabilize patient! Request for specific lab studies Consult metabolic specialist Long term treatment- based on
specific IEM
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