EXAM #2: INHERITED METABOLIC DISORDERS

Question 1

When should a metabolic disorder be considered in a child?

Answer 1

1) All neonates with unexplained, overwhelming, or progressive disease after normal pregnancy
2) All kids with acute deterioration after routine illness
3) All kids with acidosis or hypoglycemia

Question 2

What is the most common inheritance pattern of the inborn errors of metabolism?

Answer 2

Autosomal recessive

Question 3

In obtaining a history, what is paramount when an inborn error of metabolism is suspected?

Answer 3

Diet history

Question 4

What should you do if you suspect acute toxicity from an inborn error of metabolism?

Answer 4

Stop oral feeding

Question 5

What is a red flag physical exam finding in a newborn?

Answer 5

Diaphoresis (newborns should NOT sweat)

Question 6

What can grunting respirations in a child be a sign of?

Answer 6

Metabolic derangement/ acidosis

Question 7

What is the differential for a seizure in a newborn/child?

Answer 7

1) Infection
2) CNS abnormality
3) Metabolic disorder

Question 8

How are inborn metabolic errors worked up?

Answer 8

1) Electrolytes, glucose, ammonia
2) Blood, urine, CSF cultures
3) Head CT/MRI

Question 9

What is the general rule of thumb regarding abx in a newborn?

Answer 9

Error on the side of giving abx vs. not

Question 10

What is phenylalanine converted to?

Answer 10

Tyrosine

Question 11

What enzyme converts phenylalanine to tyrosine?

Answer 11

phenylalanine hydroxylase

Question 12

What is the result of the enzyme defect seen in classic PKU?

Answer 12

Autosomal recessive defect in liver phenylalanine hydroxylase that leads to:

• Increased phenylalanine
• Phenylketones

Question 13

How is PKU treated?

Answer 13

1) Restrict Phe to 250-300mg per day

2) Lofenalac

Question 14

What is malignant hyperphenylalaninemia?

Answer 14

Defect in coenzyme for phenylalanine hydroxylase

*Note that dietary Phe restriction will not improve sx.

Question 15

What are the clinical manifestations of PKU?

Answer 15

1) Choking spells
2) Feeding difficulty
3) Vomiting
4) Abnormal neurological development i.e. autism like features

Question 16

What do you need to remember about the dietary restrictions of PKU?

Answer 16

Maintain throughout life–esp. in pregnancy

Question 17

What causes galactosemia?

Answer 17

Defect in galactose 1-phospate uridylyltransferase

Question 18

What accumulates in galactosemia?

Answer 18

Galactose 1-phosphate

Question 19

What are the clinical manifestations of galactosemia?

Answer 19

• Vomiting
• Diarrhea
• Hepatosplenomegaly (HSM)
• Jaundice
• Anemia

Question 20

What are kids with galactosemia susceptible to?

Answer 20

Gram negative sepsis esp. E.coli

Question 21

How is Galactosemia diagnosed?

Answer 21

• Red cell enzyme tests

- Urine with reducing substrate

Question 22

How is Galactosemia treated?

Answer 22

1) No breast-feeding
2) No lactose/ cow’s milk
3) Switch to soy formula

Question 23

What are the three major things to monitor for in kids with Galactosemia?

Answer 23

1) Developmental delay
2) Cataracts
3) Premature ovarian failure

Question 24

What is MCAD?

Answer 24

Medium-chain acyl-CoA dehydrogenase deficiency

*Disorder of fatty acid oxidation

Question 25

What should be avoided in MCAD?

Answer 25

Fasting

Question 26

What is a typical presentation of MCAD?

Answer 26

Kid will fast all night, vomit in am, and then be comatose from hypoglycemia

Question 27

How do you tell the difference between an organic acidemia and urea cycle disorder on blood gas?

Answer 27

pCO2 and HCO3 will be LOW in BOTH

*Organic= low pH; Urea cycle= high pH