Inborn Errors of Metabolism presenting in the ED

Often our job requires us to consider the presence of needles of significant illness in the haystack of nonspecific symptoms.

Inborn Errors of Metabolism

  • For the child with neurologic abnormalities, vomiting, acidosis, hypoglycemia, organomegaly, or cardiopulmonary arrest remember to consider Inborn Errors of Metabolism (IEM) on your DDx.
  • There are over 300 disorders of the various biochemical pathways, and while the individual incidence for each disorder may be rare, the collective incidence for IEM is 1-2 / 1,000 births.
  • Treat dehydration and hypoglycemia promptly… but FIRST, think to draw EXTRA blood samples in addition to the basic labs. This will help make the diagnosis later.
  • Once you begin therapy to correct the acid/base disturbance, hypoglycemia, and dehydration the abnormal metabolites present in the serum will be reduced and possibly confound the diagnosis.

What to Order

  • Draw the extra blood, before your give the NS bolus or the Dextrose!
  • Labs to consider
    • ABG, BMP, Ammonia, U/A are helpful immediately
    • CBC, Blood and Urine Cultures (look for concurrent infection, possibly the inciting event)
    • Urine Reducing Substances, serum organic acids, urine and serum amino acids are also useful

Applegarth  DA, Toone  JR, Lowry  RB.  Incidence of inborn errors of metabolism in British Columbia, 1969–1996.  Pediatrics.  2000;105:e10.


Sean M. Fox
Sean M. Fox
Articles: 583


  1. […] Unfortunately, sometimes those seemingly straight forward cases of vomiting in fact are due to an Inborn Error of Metabolism and it requires our vigilance to make the diagnosis.  Many of us, however, also abide by the rule […]

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