Metabolism Disorders - Exam 4 Flashcards
What do congenital metabolic disorders arise from? What type of inheritance are the majority? How are they dx?
the absence or abnormality of an enzyme or its cofactor, leading to either accumulation or deficiency of a specific metabolite
autosomal recessive
Diagnosis via enzyme essays or genetic testing
What are the three products of carbohydrate metabolism?
glucose
fructose
galactose
What are the two components of sucrose? Lactose?
Sucrose = Glucose + Fructose
Lactose = galactose + glucose
_____ found in fruit, vegetables, honey, high fructose corn syrup, sucrose, sorbitol
____ is broken down from starches, lactose, maltose and sucrose
Fructose
Glucose
______ functions as the long-term storage for excess glucose. What are the two places it is stored? When is it formed?
glycogen
liver and muscle cells
Formed during periods of dietary carbohydrate loading
____ is converted to glucose for energy throughout the body and CNS. What is it responsible for?
liver glycogen
glucose homeostasis in between meals and during periods of fasting
_____ is converted to glucose during periods of ?????
muscle glycogen
high energy muscle activity
When is glycogen broken down?
Broken down when glucose demand is high or dietary availability is low
____ Defects in glycogen metabolism results in an accumulation of glycogen in the tissues. What two organ systems will determine clinical presentation?
glycogen storage diseases
liver and muscles
hypoglycemia
+/- hepatomegaly
muscle pain
cramps
rhabdomyolysis
cardiomyopathy
conduction defects
delayed growth in children
progressive weakness involving trunk and extremities
myoglobinuria
What am I?
When do s/s usually appear?
What is the tx?
glycogen storage disease
Symptoms occur after short periods of moderate to intense exercise
Avoid hypoglycemia by eating frequent smaller meals
Enzyme replacement therapy may be available for some subtypes
Treatment of complications (ie rhabdomyolysis)
What does myoglobinuria present like in a pt with glycogen storage disease?
Myoglobinuria will present as blood (heme) in urine on a dipstick. When the microscopic eval is done no RBC’s will be seen.
What are common lab findings on a pt with glycogen storage dz?
Lab findings of hypoglycemia, elevated LFT’s and/or CPK
Genetic testing
What is CPK? When it is used?
Creatinine Phosphokinase (CPK) - an enzyme that is located in the muscles, heart and the brain. When cells are damaged in these organs CPK is released.
aka enzyme released from muscle cells as they break down aka signals that muscle cells are breaking down (not a good thing)
will be high in glycogen storage dz
How is fructosemia inherited? What are the 3 subtypes?
autosomal recessive: inability to metabolize fructose
fructokinase (Essential Fructosuria)
fructose 1,6-bisphosphate aldolase - aka aldolase B (Hereditary Fructose Intolerance)
fructose 1,6-diphosphatase (FDPase) (aka fructose 1,6-bisphosphatase)
Essential Fructosuria is _____
Hereditary Fructose Intolerance is _____
FDPase is _____
fructokinase
fructose 1,6-bisphosphate aldolase - aka aldolase B
fructose 1,6-diphosphatase
_____ is a benign (asymptomatic) condition resulting from a lack of fructokinase. **What is the pathophys behind it? What is the tx?
Essential fructosuria
Incomplete metabolism of fructose in the liver leading to its excretion in urine aka fructose and sucrose just gets peed out
nothing! does NOT cause problems
Hereditary fructose intolerance is an inadequate breakdown of fructose causing a _____ of fructose-1-phosphate in the ???? (3 organs). What does it lead to?
toxic accumulation
liver, kidney and small intestine
cell death
vomiting, jaundice, hepatomegaly
crying due to abdominal pain
symptoms of hypoglycemia (lethargy/irritability/convulsions)
failure-to-thrive
infant is initially healthy and asymptomatic
What am I?
When do s/s appear?
Hereditary Fructose Intolerance
Symptoms begin upon ingestion of fructose or sucrose: usually from fruit, sweetened cereal or sucrose containing formula
formula fed babies will show signs earlier but breast fed babies will be around 4-6 months when they first are introduced to baby food
How do you confirm dx of Hereditary Fructose Intolerance? What is the tx? What are 2 common complications?
genetic testing
complete avoidance of fructose and sucrose
liver and renal failure
Which type of fructosemia enzyme def is VITAL for gluconeogenesis? What is the result?
Fructose 1,6-bisphosphatase
deficiency of FDPase results in inadequate glucose production during periods of fasting (between meals and during sleep)
aka cannot produce glucose through gluconeogenesis due to lack of the enzyme
hypoglycemia
acidosis (due to lactate build up)
respiratory rate
nausea
vomiting
lethargy
What am I?
What is the tx?
Fructose 1,6-bisphosphatase Deficiency
avoid prolonged fasting
avoid fructose
**acidosis: body compensates by trying to blow off excess CO2 (acid) and respiratory rate will be elevated
What is galactosemia? How is it inherited?
autosomal recessive
lack of metabolism of galactose leading to a toxic accumulation of galactose-related molecules in various organs
Name 4 fruits/veggies that have galactose? What is the primary source?
tomatoes, brussels sprouts, bananas, and apple
human/cow milk and baby formula
What are the three different galactosemia enzyme deficiencies? What is the MC? What is the most severe?
**Galactose-1-phosphate uridyl transferase (GALT) deficiency (type 1- Classic galactosemia)
the most common and severe type
Galactokinase deficiency (GALK)(type 2)
Galactose epimerase deficiency (GALE)(type 3)