inborn error of metabolism

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inborn error of metabolism

  1. 1.  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
  2. 2.  Individually rare, collectively a significant health problem  Approx 1:5,000 live births.
  3. 3.  Disorders of metabolism:  Amino acids  Carbohydrates  Fatty acid  Lysosomal and peroxisomal function  Mitochondrial  Organic acids
  4. 4.  May be gradual  May be sudden  May be catastrophic
  5. 5.  Infectious disease  Respiratory  Cardiac  GI  Neurological
  6. 6.  Metabolic acidosis  Hyperammonemia  Hypoglycemia
  7. 7. 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
  8. 8. 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
  9. 9. Copyright ©1998 American Academy of Pediatrics
  10. 10.  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
  11. 11.  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, dehydratio n.  Sepsis + ABx if uncertain.  Pyridoxine for neonatal sz. if AED no-response  .
  12. 12.  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?
  13. 13.  No acidosis (respiratory alkalosis)  No ketones (unlike organic acidemia)  No hypoglycemia  But with hyperammonemia
  14. 14.  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
  15. 15.  Prognosis: guarded  Even with Treatment, many will die  Definitive treatment: liver transplant
  16. 16.  Healthy NB rapidly ill, › Ketoacidosis, poor feeding  Vomiting, dehydration  Hypotonia, lethargy  Tachypnea, seizures  Coma, unusual odors Organic acidemia
  17. 17.  Labs:  Urine organic acids  Ketonuria (in the NB)- pathognomonic of IEM  Neutropenia, thrombocytopenia  +/- hyperammonemia  Abnormal acylcarnitine
  18. 18.  Treatment:  Stabilize  Get rid of organic acid intermediates, and ammonia- dialysis  Carnitine  After stabilization, may resume oral feeds  Consult dietitian, and metabolic specialist
  19. 19.  **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
  20. 20.  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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