Inborn errors of metabolism: Difference between revisions
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==Clinical Features== | ==Clinical Features== | ||
Exam and history: | Exam and history: | ||
* | *Lethargy (secondary to hyperammonemic [[encephalopathy]]) | ||
*[[Nausea]]/[[vomiting]] | *[[Nausea]]/[[vomiting]] | ||
*Difficulty feeding | *Difficulty feeding | ||
| Line 14: | Line 14: | ||
*Unusual odors | *Unusual odors | ||
*Hypotonia | *Hypotonia | ||
*Encephalopathy | *[[Encephalopathy]] | ||
*[[Hypoglycemia]] | *[[Hypoglycemia]] | ||
*Hepatic dysfunction | *Hepatic dysfunction | ||
| Line 39: | Line 39: | ||
#IVF | #IVF | ||
#*[[Normal saline]] 20 mL/kg boluses | #*[[Normal saline]] 20 mL/kg boluses | ||
#*Once rehydrated, switch to IVF with dextrose (D10) at 1-2x maintenance | #*Once rehydrated, switch to IVF with [[dextrose]] (D10) at 1-2x maintenance | ||
#*Increases renal excretion of toxic metabolites | #*Increases renal excretion of toxic metabolites | ||
#Hyperammonemia | #Hyperammonemia | ||
#*<500 | #*<500 | ||
#** | #**[[sodium phenylacetate/sodium benzoate]] 250mg/kg in D10 over 90min; then 250mg/kg/d infusion | ||
#**Arginine 210mg/kg IV/IO in D10 over 90min; then 210mg/kg/d infusion | #**Arginine 210mg/kg IV/IO in D10 over 90min; then 210mg/kg/d infusion | ||
#*>500 | #*>500 | ||
#**Dialysis | #**Dialysis | ||
# | #Sodium [[bicarbonate]] if acidotic | ||
===Cerebral edema=== | ===Cerebral edema=== | ||
*Hyperammonemia is risk factor | *Hyperammonemia is risk factor | ||
** | **[[Mannitol]] 0.5gm/kg IV/IO | ||
**Do not give steroids (worsens hyperammonemia) | **Do '''not''' give steroids (worsens hyperammonemia) | ||
===If seizing=== | ===If seizing=== | ||
*consider | *consider [[vitamin B6]] (pyridoxine) | ||
===Subsequent Management=== | ===Subsequent Management=== | ||
Revision as of 21:23, 24 December 2016
Background
- Suspect in any sick neonate
- Newborn screening varies by state
- May present as late as early childhood
- Clinical manifestations are due to accumulation of toxic metabolites
- Must rule-out sepsis (more common in these patients)
Clinical Features
Exam and history:
- Lethargy (secondary to hyperammonemic encephalopathy)
- Nausea/vomiting
- Difficulty feeding
- Seizure
- Unusual odors
- Hypotonia
- Encephalopathy
- Hypoglycemia
- Hepatic dysfunction
Differential Diagnosis
Sick Neonate
THE MISFITS [1]
- Trauma
- Heart
- Congenital heart disease
- Hypovolemia
- Endocrine
- Metabolic
- Sodium
- Calcium
- Glucose
- Inborn errors of metabolism
- Seizure
- Formula / feeding problems
- Intestinal Disasters
- Toxin
- Sepsis
Evaluation
- Glucose level
- Ammonia
- Should be <200 in normal neonate (higher suggests urea cycle disorders)
- Lactate
- Chemistry
- Anion gap associated organic acidemias
- May see hypoglycemia, metabolic acidosis
- Urinalysis (ketones)
- LFT
- VBG
Management
Must stop catabolism and acculmulation of toxins/ammonia
- Keep NPO
- Removes potential inciting metabolic substrates
- IVF
- Normal saline 20 mL/kg boluses
- Once rehydrated, switch to IVF with dextrose (D10) at 1-2x maintenance
- Increases renal excretion of toxic metabolites
- Hyperammonemia
- <500
- sodium phenylacetate/sodium benzoate 250mg/kg in D10 over 90min; then 250mg/kg/d infusion
- Arginine 210mg/kg IV/IO in D10 over 90min; then 210mg/kg/d infusion
- >500
- Dialysis
- <500
- Sodium bicarbonate if acidotic
Cerebral edema
- Hyperammonemia is risk factor
- Mannitol 0.5gm/kg IV/IO
- Do not give steroids (worsens hyperammonemia)
If seizing
- consider vitamin B6 (pyridoxine)
Subsequent Management
- Consider L-carnitine in conjunction with specialist, as some diseases may respond (but has side effects)
See Also
References
- ↑ Brousseau T, Sharieff GQ. Newborn emergencies: the first 30 days of life. Pediatr Clin North Am. 2006 Feb;53(1):69-84, vi.