Inborn Errors Of Metabolism Flashcards
What are the main organic acidemias?
“GIMP”
Glutaric acidemia
Isovaleric acidemia
Methylmalonic acidemia
Propionic acidemia
What are the features of organic acidemias?
Glucose: Low NH3: High Ketones: Yes Acidosis: Yes Lactate: High
- DOL 2
- Thrombocytopenia, granulocytopenia
- Dx: urine organic acid levels
- Tx: hydration, stop protein intake, IV glucose and ammonia scavengers, L-carnitine
What are the features of urea cycle defects?
Glucose: Nml NH3: High!!! (low BUN) Ketones: No Acidosis: No Lactate: Nml
- OTC, Citrullinemia, ASA
- Hypotonia
- Respiratory alkalosis
- Vomiting
- Lethargy
- Dx: check serum citrulline, arginine, ASA, urine orotic acid. low arginine, no citruline, high urine orotic acid.
- Tx: restrict protein, NH3 scavengers (benzoate, phenylbutarate)
What are the features of fatty acid metabolism disorders?
Glucose: Low NH3: Nml/High Ketones: No Acidosis: Mild Lactate: High
- MCAD, LCAD, VLCAD
- Induced by stress, fasting -> nonketotic hypoglycemia
- Do not present in the first week of life
- Possible hepatomegaly with transaminitis
- Dx: low glucose and low ketones. Get carnitine and acylcarnitine levels.
- Tx: IV glucose
What are the features of storage diseases?
Glucose: Low NH3: Nml Ketones: Yes Acidosis: Yes (gap acidosis) Lactate: High
- GSD1, GSD2
- Organomegaly (from glycogen buildup)
- Dx: low fasting glucose + ketones
- Tx: cornstarch
What are the features of mitochondrial disorders?
Glucose: Low NH3: Nml Ketones: Yes Acidosis: Yes Lactate: High
Same as storage disorders
- Elevated pyruvate level, lactic acid level, uric acid level
What are the features of amino acidopathies?
Glucose: Nml NH3: Nml Ketones: No Acidosis: No Lactate: Nml (except in MSUD)
- Subtypes: "PATH" P: PKU A: Alkaptonuria T: Tyrosinemia H: Homocysteinuria
- Dx: high levels of specific amino acid that cannot be broken down in serum and urine
- Tx: Limit intake of specific amino acid
What are the features of hyperglycinemia?
Glucose: Nml NH3: Nml Ketones: No Acidosis: No Lactate: Nml
- Seizures, hiccups, lethargy
- Dx: high glycine
- poor prognosis
What are the features of galactosemia?
Glucose: Low NH3: Nml Ketones: Nml Acidosis: No Lactate: Nml
- GALT deficiency
- Patients present with GNR sepsis
- Can present with vomiting, diarrhea, lethargy, hepato-megaly, jaundice, hypoglycemia, seizures
- Dx: high g1p, non-glucose reducing substances in urine, low GALT activity in RBCs
- Tx: lactose and galactose free diet
What are the features of isovaleric acidemia?
Sweaty feet smell Poor feeding Seizures Prone to getting infections No lactic acidosis Treatment: protein restriction
What are the features of methylmalonic acidemia and propionic acidemia?
Poor feeding Vomiting Dehydration Lethargy Hypotonia Tachypnea
MMA: tx with B12
Propionic: tx with biotin
What are the features of ornithine transcarbamylase deficiency?
- X-linked (much more symptomatic in boys than in girl carriers, who only get symptoms when they are sick)
- High urine orotic acid
What are the features of von Gierke’s disease?
- GSD I
- Glucose-6-phosphatase deficiency -> can’t break down glycogen -> glycogen deposits in organs
- Doll like face
- Only presents when there is hypoglycemia
- Hypoglycemia, ketoacidosis (from fat breakdown), lactic acidosis, hyperuricemia
- Tx: low carb diet, complex carbs (cornstarch)
What are the features of Pompe disease?
- GSD II
- Lysosomal disorder: deficiency of lysosomal alpha 1,4 glucosidase
- Presentation: baby with hypotonia, macroglossia, and hypertrophic cardiomyopathy
- Glycogen deposits in organs -> organomegaly
- No hypoglycemia because other glycogen stores can be broken down
- Dx: ⬆️ glycogen in lysosomes, ⬆️ LDH, ⬆️ CK
What are the aminoacidopathies?
“PAM is a Hot tamale.”
P: Phenylketonuria
A: Alkaptonuria
M: Maple syrup urine disease
H: Homicysteinuria