Metabolic

Question 1

What is the defect involved in Glycogen Storage Disease type 1? Gierke disease

Answer 1

Deficiency of glucose-6-phosphatase
Converts glucose-6-phosphate into glucose as final step in glycogenolysis pathway

Growth retardation
Cherubic facies

Question 2

What is the treatment approach to Glycogen storage disease I?

Answer 2

Diet should be 70% carbs Preventing hypoglycaemia
Cornstarch given at bedtime can prevent hypo overnight
No role for adding tricglycerides or proteins

Question 3

For inborn errors of metabolism, how do you differentiate between those caused by accumulation of anions vs loss of bicarbonate ?

Answer 3

Normal chloride, raised anion gap

Raised chloride, normal anion gap

Question 4

What test would you next order for a raised IRT (immunoreactive trypsinogen) on newborn screen? What is the overall sensitivity ?

Answer 4

Delta F508 on DNA testing to look for CF
75% sensitivity
Then sweat test if positive

Question 5

What is the most likely diagnosis:

1 month old with poor feeding, irritability, opisthotonus, seizures

Normal pH, glucose, lactate, ammonia
Raised ketones
Increased plasma leucine
And what is the treatment

Answer 5

Maple syrup Urine Disease

Avoid intake of leucine: 
Special formula (branched chain amino acid free) 

Prevent catabolism:
Energivit
IV intralipids

Can still breastfeed but after energivit and controlled volumes

Question 6

What is the most likely diagnosis?
Present with coma/seizure / poor feeding/ lethargy / floppiness in neonate
Metabolic acidosis (high AG), low glucose
Raised ammonia, lactate, ketones

Improves with IV fluids but worsens with feeds

And what is the treatment

Answer 6

Methylmelonic acidosis
Organic acidopathy

Low protein diet
Avoid prolonged fasts

Question 7

What is the most likely diagnosis ?
What is the treatment

3 yo found unresponsive with Hypoglycaemia after gastro with poor intake but no ketones

Answer 7

MCAD
(Medium chain acyl coA reductase deficiency)
Fatty acid oxidation defect - can’t produce ketones for energy during fasting

Emergency: IV fluids + dextrose
Avoid prolonged fasting

Question 8

What is the most likely diagnosis?

What is the treatment ?

5 day old boy poor feeding, decreased responsiveness/coma
Metabolic alkalosis
High ammonia
Normal ketones, glucose, lactate

Mum has an aversion to meat

Answer 8

OTC deficiency (ornithine transcarbomylase deficiency) 
Urea cycle defect -  can’t convert ammonia to urea 

Low protein diet
Prevent catabolism
Arginine/citrulline

Can give sodium benzoate (increase disposal of metabolites)

Question 9

What is the most likely diagnosis ?
What test would you choose to confirm diagnosis ?

3 month old with hypotonia, high forehead/dysmorphic, hepatomegaly

Normal gas
Normal glucose, ammonia, lactate, ketones

Answer 9

Zellweger syndrome
Peroxisomal disorder

Serum VLCFAs

Question 10

What is the most likely diagnosis and what test would conform the diagnosis?

10 yo boy with personality change, decreased school performance, skin pigmentation

Answer 10

Adrenoleukodystrophy
Peroxisomal disorder

VLCFAs