Inborn errors of metabolism: Difference between revisions
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==Evaluation== | ==Evaluation== | ||
*Glucose level | *Physical Exam: | ||
*Ammonia | **Organomegaly | ||
**Should be <100 in normal neonate | **Neuro exam - tone, reflexes | ||
*Lactate and pyruvate (drawn at same time) | **Skin rashes | ||
*Chemistry | **Eye exam | ||
**Anion gap (if >20, suggests | *Labs: | ||
**May see hypoglycemia, [[metabolic acidosis]] | **Glucose level | ||
*[[Urinalysis]] (for ketones) or beta hydroxybutyrate in serum (very helpful to obtain prior to giving dextrose in hypoglycemic patients, if possible) | **Ammonia | ||
* | ***Should be <100 in normal neonate | ||
*VBG | **Lactate and pyruvate (drawn at same time) | ||
**Chemistry, hepatic panel | |||
***Anion gap (if >20, suggests an organic acidemia) | |||
***May see hypoglycemia, [[metabolic acidosis]] | |||
**[[Urinalysis]] (for ketones) or beta hydroxybutyrate in serum (very helpful to obtain prior to giving dextrose in hypoglycemic patients, if possible) | |||
**CBC | |||
***multiple organic acidemias can cause cytopenias | |||
**VBG | |||
**CPK in older kids and adolescents | |||
*Additional studies: | |||
**Consider head CT | |||
==Management== | ==Management== | ||
Revision as of 03:37, 31 March 2017
Background
- Suspect in any sick neonate
- Newborn screening varies by state
- May present as late as early adulthood
- 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
- Physical Exam:
- Organomegaly
- Neuro exam - tone, reflexes
- Skin rashes
- Eye exam
- Labs:
- Glucose level
- Ammonia
- Should be <100 in normal neonate
- Lactate and pyruvate (drawn at same time)
- Chemistry, hepatic panel
- Anion gap (if >20, suggests an organic acidemia)
- May see hypoglycemia, metabolic acidosis
- Urinalysis (for ketones) or beta hydroxybutyrate in serum (very helpful to obtain prior to giving dextrose in hypoglycemic patients, if possible)
- CBC
- multiple organic acidemias can cause cytopenias
- VBG
- CPK in older kids and adolescents
- Additional studies:
- Consider head CT
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.