inborn errors of metabolism

1. Approachto IEM
History
• Age of onset Neonatal period—Galactosemia,organicacademia
 Afterintroductionof complementaryfeeds— Disordersof fructose metabolism
• Consanguinity—suggeststhe possibilityof metabolicdisorder(MostIEMsare autosomal
recessive)
• Timingof symptoms
- EarlymorningafterprolongedfastingusuallyoccursinGSD, FAO
Well afterbirthandsymptomsafterthe introductionof breastfeedsusuallysuggestanIEM
• Prolongationof physiological jaundice,Escherichiacoli sepsismaysuggestgalactosemia
• Symptomssuggestive of sepsislikevomiting,lethargy,failure tothrive,andpoorfeedingoften
occurs inmetabolicdisorders(IEMmimickssepsis;
• Historyof previousrecurrentabortions,earlyneonatalandprevioussiblingdeaths,familyhistory
of developmental delayandseizuresstronglysuggestthe likelihoodof ametabolicdisorder
Examination
• Doll faciescanoccur in Glycogenstorage disorders
• Cataract are commonlyseeningalactosemia
• Icteruscan occur in galactosemiaandotherIEMwithliverdysfunction
• Isolatedhepatomegalyoccursintype 1 Glycogenstorage disorder(VonGierke’sdisease)
• Hepatosplenomegalycanoccurin galactosemia,type 3,and4 GSD
Investigations
• Critical bloodsample tobe takenatthe time of hypoglycemia(itincludesglucose,freefattyacids,
ketones,lactate,uricacid,ammonia,insulin,cortisol,growthhormone)
• Serumammonia
• Arterial bloodgasforpH
• Serumlactate
• Blood/urinary ketones(nonketotichypoglycemiacanoccur infatty acidoxidationdefects;ketotic
hypoglycemiacanoccur in GSD type 1 andvariouscarbohydrate metabolicdisorders)

2. • Bloodcounts(leucopeniaandneutropeniacanoccur in organicacademia)
• Septicscreeningandbloodculture torule outsepsis
• Urine for reducingsubstances(positiveingalactosemia)
• Urine metabolicscreening
• Serumtriglycerides,serumuricacidelevationintype 1 GSD
Liverbiopsyincase of type 1 GSD maybe required
Treatment
• Correcthypoglycemia(10%dextrose) andperformstabilizationmeasures.
• Treatmentdependsonthe cause