Inborn errors of metabolism
Background
Over hundreds of diseases
Suspect in any sick neonate
Newborn screening varies by states, California tests for 29 major diseases
May present as late as early childhood
Diagnosis
Exam and history:
- Lethargic (2/2 hyperammonia encephelopathy)
- Nausea/vomiting
- Difficulty feeding
- Seizure
- Strange odors
- Hypotonia
Work-Up
Elevated Ammonia
- Key to suspect diagnosis, however there are a few diseases where ammonia may be normal
- +/- Hypoglycemia, metabolic acidosis, anion gate, elevated lactate, ketones
Sepsis work up usually concomitant, if patient is ill as these children are prone to infections
DDx
in neonates: THE MISFITS
see Neonatal Resuscitation
Treatment
Must stop catabolism and acculmulation of toxins/ammonia
- IVF with Dextrose at 1-1.5x maintenace
- Don't feed
- Dialysis (ammonia >500)
- NaBicarb if acidotic
- Consider L-carnitine in conjuction with specialist, as some diseases may respond (but has side effects)
- Antibiotics-- assume sepsis
- if seizing-- consider Vit B6/pyroxidine
See Also
see Neonatal Resuscitation
