Inborn Errors of Metabolism

U4 P1

T/F Patients with inborn errors of metabolism usually present immediately after birth

false (usually do NOT immediately present after birth)

T/F Patients with inborn errors of metabolism are typically chronically and consistently ill

false (there are typically well intervals)

When is diagnostic testing for inborn errors of metabolism most effective?

A) immediately after birth

B) after age 2

C) during toxic presentation

D) anytime

C (during toxic presentation)

Which of the following is LEAST suggestive of toxic presentation of inborn errors of metabolism?

A) encephalopathy

B) fever

C) vomiting, poor feeding, or fasting

D) metabolic alkalosis

E) lethargy

D (metabolic ACIDOSIS)

Which of the following is NOT a consequence of inborn errors of metabolism?

A) seizure and ataxia

B) jaundice and hepatomegaly

C) cataracts

D) cardiomyopathy

E) all of the above

E (all of the above)

Encephalopathy with fever, poor feeding, and metabolic acidosis indicates which type of presentation of inborn error of metabolism?

A) Toxicity

B) Specific organ involvement

C) Energy deficiency

D) Dysmorphic findings

E) Appearance of organ storage

A (Toxicity)

Disorders of carbohydrate metabolism and/or mitochondrial function would present as which type of error of inborn metabolism?

A) Toxicity

B) Specific organ involvement

C) Energy deficiency

D) Dysmorphic findings

E) Appearance of organ storage

C (Energy deficiency)

(will see myopathy, CNS dysfunction, vomiting, renal tubular acidosis, CM, and hypoglycemia)

Which presentation of errors of inborn metabolism is caused by accumulation of incompletely metabolized large molecules (which can deposit in different tissues)?

A) Toxicity

B) Specific organ involvement

C) Energy deficiency

D) Dysmorphic findings

E) Appearance of organ storage

E (Appearance of organ storage)

Most errors of inborn metabolism are inherited in an autosomal (dominant / recessive) manner

recessive (carriers are asymptomatic and a few are X linked)

When should screening for errors of inborn metabolism occur?

A) immediately after birth

B) by age 1

C) with onset of symptoms

D) between 24-72 hours after feeding

D (between 24-72 hours after feeding -- need the exposure)

(ANY positive screening MUST be promptly evaluated)

Errors of inborn metabolism can be confused with several other disease processes (sepsis, GI obstruction, cardiac defect). All of the following symptoms increase suspicion for inborn errors of metabolism EXCEPT:

A) acidosis or AMS out of proportion to other findings

B) severe hypotonia or hypertonia

C) fever

D) unusual odor

E) hiccoughs

F) organomegaly

G) abnormally brittle hair

C (fever)

A musty, mousy, wet fur smell indicates which error of inborn metabolism?

A) maple syrup urine disease

B) tyrosinemia

C) Phenylketonuria

D) cystinuria

E) homocystinuria

C (PKU)

A cabbage-like smell indicates which error of inborn metabolism?

A) maple syrup urine disease

B) tyrosinemia

C) Phenylketonuria

D) cystinuria

E) homocystinuria

B (tyrosinemia)

Which error of inborn metabolism results from an inability to break down the amino acid phenylalanine to tyrosine which results in an accumulation of phenylalanine and becomes toxic to organs?

A) maple syrup urine disease

B) tyrosinemia

C) Phenylketonuria

D) cystinuria

E) homocystinuria

C (Phenylketonuria)

In PKU, phenylalanine accumulates and becomes toxic to organs, primarily the:

A) brain

B) liver

C) bones

D) skin

A (brain) (Phenylalanine is particularly neuro-toxic to the developing brain - causes encephalopathy, MR, and microcephaly)

Which of the following is the diagnostic test for PKU?

A) low tyrosine

B) elevated phenylalanine

C) elevated phenylalanine and low tyrosine

D) low phenylalanine and elevated tyrosine

C (elevated phenylalanine and low tyrosine)

Which of the following is the screening test for PKU?

A) low tyrosine

B) elevated phenylalanine

C) elevated phenylalanine and low tyrosine

D) low phenylalanine and elevated tyrosine

B (elevated phenylalanine)

What is treatment for PKU?

A) IVIG and steroids

B) oral tyrosine replacement

C) restriction of natural proteins and aspartame

D) plasma pheresis

C (restriction of natural proteins and aspartame)

(strict vegetarian diet and metabolic formula)

T/F The fetus of a pregnant patient with uncontrolled PKU may develop microcephaly and severe MR without having PKU

true (phenylalanine is neurotoxic to the developing brain)

Which inborn error of metabolism results in elevated tyrosine levels secondary to an absence or malfunction of enzymatic breakdown?

A) maple syrup urine disease

B) tyrosinemia

C) Phenylketonuria