Hypoglycemia Flashcards
what blood glucose levels are considered to be hypoglyemia?
specify for each population.
- in adults w/out diabetes: < 50 mg/dL (2.8 mmol/L)
- in people with diabetes: < 70 mg/dL (3.9 mmol/L)
- in newborns: < 40mg/dL (2.2 mmol/L)
when do symptoms of hypoglycemia tend to appear?
at blood glucose < 50 mg/dL
symptoms of hypoglcyemia?
- sweating / papitations
- irritability / anxiety / confusion
- headache / dullness / fatigue
- extreme cases : –> seizure, brain dysfunction, coma
what is whipple’s triad?
the three criteria that must be met for dx of symptomatic hypoglycemia::
- Symptoms of hypoglycemia
- Plasma [glucose] < 50 mg/dl
- Amelioration of symptoms by restoration of normal plasma [glucose]
what are the main causes of hypoglycemia?
which one is the m/c?
-
drug induced hypoglycemia
- non-titrated insulin dose / insulin without food
- sulfonlyurea therapy
- ethanol
- tumors - eat up all the glucose
- counter regulatory hormone defiency- any non-insulin glucose regulator (glucagon, epi, GH, glucocorticoids)
- hepatic disorders
- glycogen storage diseases - defect in debranching enyzme, g. phosphorylase, phosphorylase kinase
what are the major causes of drug-induced hypoglycemia?
= m/c cause of hypoglycemia
-
diabetes drug therapy
- insulin - incorrect dose, taking w/out food
- sulfonyureas, repaglinide
-
ethanol - induces hypoglycemia by inhibiting gluconeogenesis:
- in the body, ethanol is oxidized to acetic acid, which eats up 2 NAD+ molecules.
- this depletes NAD+ that can be used to
- convert lactate –> pyruvate
- convert malate –> OAA (malate asparate shuttle)
- this depletes NAD+ that can be used to
- in the body, ethanol is oxidized to acetic acid, which eats up 2 NAD+ molecules.
how does ethanol inhibit gluconeogenesis?
how does this often present clinically?
- in the body, ethanol is oxidized to acetic acid, which eat up 2 NAD+ molecules.
- this depletes NAD+ that can be used to
- convert lactate –> pyruvate
- malate –> OAA (moves OAA to cytosol)
- thus impairing key gluconeogenic steps & substrate usage
- this depletes NAD+ that can be used to
- a classical clinical picture is a pt with:
- hypoglcyemia (< 50 mg/dl)
- along with:
- high blood alcohol
- high blood lactate
- low pH (acidosis)
- deep breathing (resp compensation)
metabolic acidosis d/t lactic acidosis, which is d/t accmulating lactate from impaired conversion to pyruvate
which tumors induce hypoglycemia and how?
- insulinoma - unregulated insulin secretion from pancreas
- all other tumors - utilize great amounts of blood glucose
what are “glycogen storage diseases”
a group of inherited disorders defined by
- deposition of abnormal type/quantity of glycogen
- failure to mobilize glycogen
von Gierke’s disease
- what type of glycogen storage disease?
- presentation?
- tx
- Type I: deficiency of glucose-6-phosphotase - the only enzyme that can release glucose from glycogen for tissue use (mobilization defect)
- presentation:
- SEVERE hypoglycemia
- lactic acidosis
- tx - dietary
Pompe’s storage disease
- what type of glycogen storage disease?
- clinical presentation?
- tx?
- Type III: deficiency of lysosomal a1,4 glucosidase an enzyme that degrades glycogen in lysosomes. large glycogen vacuoles accumulate in cells (deposition defect)
- clinical presentation:
- cardiomegaly / heart failure
- normal blood glucose
- tx - none
Cori’s disease
- what type of glycogen storage disease
- clinical presentation
- treatment\
- type III: deficiency of debranching enzyme resulting in inc [glycogen] + shorter outer branches (mobilization / deposition defect)
- presentation:
- hepatomegaly
- mild hypoglycemia
- tx - dietary
Anderson’s
- what type of glycogen storage disease
- clinical presentation
- tx
- type IV: defect in branching enzyme: normal glycogen [] with long filamtenous structure (deposition defect)
- presentation:
- hepatomegaly, cirrhosis
- normal blood glucose
- early death d/t liver failure
Tarui’s
- what kind of glycogen storage disease
- what clihnical effects
- tx
- type VII: deficiency of muscle phosphofructokinase. impaired glycolysis leads = accumulating glucose –> glycogen synthesis. increased glycogen [] w/ normal structure
- clinical presentation - exercise intolerance
- tx - avoid strenous exercise
Type VIII glycogen storage disease?
- deficiency in what enzyme?
- has what effects?
- deficiency of liver phosphorylase kinase
- increased glycogen [] - normal structure
- liver affected
fructosuria?
which enzyme effected?
how does it affected the fructose metabolism path?
clinical presentation?
- deficiency of fructokinase
- fructose accumulates in blood –> appears in urine
- clinical
- fructosuria
- otherwise asmptomatic
hereditary fructose intolerance
which enzyme effected?
how does it affected the fructose metabolism path?
clinical presentation?
- deficiency of aldolase B
- fructose -1- P accumulates
- this uses up all the Pi, reducing Pi pool. this inhibits
- glycogenolysis - glycogen phosphorylase (relies on P)
- glycolysois - aldolase A (relies on P)
- this uses up all the Pi, reducing Pi pool. this inhibits
- clinical:
- severe hypoglycemia
- abdominal pain / vomitting
- infant death
galactosemia
- caused by deficiency of what enzyme?
- effects glucose metabolism how?
- clinical presentation?
non-classical galactosemia
- galactokinase deficiency
- galactose accumulates
- clinical:
- cataracts
classical galactosemia
- transferase deficiency
- galactose + Gal-1-P accmulates
- clinical:
- cataracts
- growth failure / mental retardation
