Metabolics Flashcards
Hyperammonemia, what to check next
Assess for acidosis and ketouria
Etiologies of hyperammonemia and acidosis without ketosis
FAOD
Hyperammonemia without acidosis or ketosis etiology
Check plasma citrus line
Hyperammonemia with ketosis and acidosis etiology
Lactic acidemia
Glutaric aciduria
Pyruvate carboxylase deficiency
B methylcrotonyl glycinuria
Propionic, methylmalonic and isovaleric acidurias
Initial evaluation of an infant with possible metabolic disorder
CBC (for neutropenia and thrombocytopenia)
Electrolytes and arterial blood gas (for acidosis/alkalosis, anion gap)
Glucose
Calcium
Plasma ammonia
Lactate and pyruvate
LFTs
PT
Ketones
Reducing substances
NBS
Secondary evaluation for targeted eval of infant with possible metabolic disorder
PAA
UOA
plasma carnitine and acylcarnitine profile
Plasma uric acid
BHOB and FFA
CSF amino acid analysis
Peroxisomal function tests
Galactosemia cause, inheritance, symptoms
Galactose 1 phosphate uridyl transferase - if absent classic Galactosemia
AR
Poor feeding, vomiting, jaundice, liver failure, lethargy, renal, tubular, dysfunction, hepatomegaly , E. coli infections
Labs: increased LFT, increased indirect bili and later elevated d bili, low glucose, increased galactose in urine
Next steps after abnormal galactose on NBS
Change to non lactose diet
Check lft, urine reducing substances, galactose 1 phosphate
Quantitative rbc GALT assay 
Galactokinase deficiency
Inheritance, clinical presentation, abnormal newborn screen 
AR
Cataracts
If elevated galactose and normal RBC GALT
Test for urine reducing substances and then test for galactokinase if present reducing substances OR test epimerase if absent reducing substances
Glycogen storage diseases that effect liver
Also have direct influence on blood glucose
Type I (Von gierke), 6 (Hers), 8
GSD that effect muscle and anaerobic work
Type 5 (mcardle) and 7 (tarui)
GSD that effect both liver and muscle
Type 3 (Forbes)
GSD that affect various tissues yet no direct effect on blood glucose or anaerobic function
Type 2 (pompe) and type 4 (Andersen)
Neonatal presenting GSD
Von gierke (type 1) and pompe (type 2)
Type 1 GSD enzyme deficiency
Glucose 6 phosphatase
Type 2 GSD enzyme deficiency
Lysosomal alpha glucosidase
Deficiencies that cause hereditary fructose intolerance
And lab findings
Fructokinase
Fructose 1-phosphate aldolase
Findings: low glucose because of blockage of glycogenolysis (F1P inhibits phosphorylase activity and inhibits gng)
Absence of enzyme F1P adolase
Abnormal LFTs
Reducing substances in urine
Urea cycle defects presentation
Majority present after age 1 or 2 days
Poor oral intake
Vomiting
Tachypnea
Lethargy followed by hypotonia
Seizures
Signs of liver disease
Lab findings of UCD
Severe hyperammonemia
Primary resp alkalosis (maybe from cerebral edema if hyoerammonemia)
Normal glucose
UCD pathway
Page 102 of review book
how to diagnosis UCD
SAA
UOA (orotic acid)
Fibroblast or hepatocyte enzyme activity
Diagnosis for N acetylglutamate synthetase
Glutamine/alanine: high
Urine orotic acid: low
Citrulline: low
Arginine: low
Diagnosis of Carbamyl phosphate synthetase
Glutamine/alanine: high
Urine orotic acid: low
Citrulline: low
Arginine: low
Diagnosis of ornithine carbamyl transferase
Glutamine/alanine: high
Urine orotic acid: high
Citrulline: low
Arginine: low
Diagnosis of argininosuccinic acid synthetase
Glutamine/alanine: high
Urine orotic acid: high
Citrulline: high
Arginine: low
Diagnosis of arginosuccinic lyase deficiency
Glutamine/alanine: high
Urine orotic acid: high
Citrulline: high
Arginine: low
Deficiency of arginase to argininemia diagnosis
Glutamine/alanine: high
Urine orotic acid: high
Citrulline: high
Arginine: high
Treatment of UCD - hyperammonemia
Neurologic outcomes correlate with duration of hyperammonemia
Hydration
Remove nitrogen via medications (sodium benzoate and sodium phenylacetate) - renal function necessary because excreted in urine
Hemodialysis if ammonia >500
Eliminate protein and minimize catabolism
Provide IV glucose
Supplement with arginine
Maple syrup urine disease deficient
Ketoacid dehydrogenases that require thiamine
Maple syrup urine disease lab findings
Send urine ketones, SAA, UOA
Ketonuria
Hypoglycemia
Maple syrup urine odor
Metabolic acidosis
Urine dinitrophenylhydrazine test -> forms white precipitates
Definitive: ketoacid dehydrogenase assay of skin fibroblasts of WBCs
Prenatal dx: decreased keroacid dehydrogenase activity in cultured amniocytes or choriovillus cells
Maple syrup urine disease s/s
Usually within first few days to weeks
Poor feeding
Vomiting
Lethargy
Tachypnea
Death if untreated
By 4 days, neurologic abnormalities: lethargy, irritability, alternating hypotonia and hyerptonia, dystonia, apnea, seizures, signs of cerebral edema
MSUD neurologic outcome a/c
Correlate with plasma leucine concentrations
