L29 Hypoglycemia Flashcards
What is the definition of adult hypoglycemia?
Plasma glucose <2.5 mmol/L by laboratory method
One of the causes of hypoglycemia is excessive glucose utilization. List 4 sub-causes.
- Insulin administration
- Oral hypoglycemic
- Insulinoma
- Extra-pancreatic tumors
One of the causes of hypoglycemia diminished glucose production. List 4 sub-causes.
Briefly describe each cause.
- Primary/secondary adrenal insufficiency (MC)
- GH deficiency
- depleted cortisol increases insulin sensitivity - Liver disease
- reduced glycogen reserve in cirrhosis - Renal disease
- multifactorial
- uremia inhibits liver gluconeogenesis and causes poor appetitie, reduced insulin clearance - Autoimmune cause
- agonist auto Ab to the insulin receptor
- agonist auto Ab to beta cells
Insulin administration overdose
What to expect to see in serum insulin and C-peptide? (2)
Serum insulin increased
C-peptide reduced
(exogenous insulin suppresses endogenous insulin secretion. )
List examples of hypoglycemic drugs. (2)
Meglitinides, glyburide, DPP-4 inhibitors
TZD (thiazolidinedione) in combination with metformin
What to expect to see in serum insulin and C peptide in hypoglycemia caused by oral hypoglycemics? (2)
How to differentiate this cause from insulinoma? (1)
Serum insulin increased
C peptide increased
Urine drug screen
What is Whipple’s triad in hypoglycemia?
- Low plasma glucose concentration measure with a laboratory method
- Symptoms consistent with hypogly
- Relief of those symptoms after plasma glucose is raised
List some symptoms of hypogly.
Fall in blood glucose stimulates the release of catecholamines which results in symptoms such as sweating, tremor, anxiety, hungriness.
What is neuroglycopenia? List some symptoms
Poor concentration, delirium, convulsions, slurred speech
due to decreased CSF glucose level
Insulinoma:
serum insulin and C-peptide? (2)
High serum insulin
High C-peptide even during fasting (at all times)
Pathophysiology of an insulinoma?
Secretion of insulin and C-peptide ratio?
Pancreatic islet adenoma that produces insulin and C-peptide in equimolar ratio
may have family history of MEN (multiple endocrine neoplasia)
Examples of extra-pancreatic tumors?
- Retroperitoneal fibrosarcoma
2. Hepatoma
Pathophysiology of extra-pancreatic tumors?
- Increase “big” IGF-2 or similar molecule (insulin-like growth factor)
- Suppression of insulin and GH
- Reduced IGFBP3 and IGF-1, increased free IGF-2
- Reduced hepatic glucose production + increase glucose uptake by peripheral tissues
How to diagnose extra-pancreatic tumors causing hypoglycemia? (4)
- low serum Insulin
- low C-peptide
- high IGF-2
- low IGFBP3
How to diagnose adrenal insufficiency cause of hypoglycemia?
Short synacthen test;
Glucagon stimulation test
(glucagon should come out and help normally!)
Reactive hypoglycemia happens after food intake (post-prandial).
It can be due to 2 causes?
- Autoimmune cause
- Post-gastrectomy syndrome
- Post-gastrectomy syndrome
- Rapid absorption of glucose > excessive insulin response
Tx: small meals, more complex carbohydrates
- diagnosed by extended OGTT and history taking
In reactive hypoglycemia due to autoimmune cause, there is agonist autoAb to ___________, causing?
insulin;
initial hyperglycemia by binding insulin > subsequent hypoglycemia by releasing insulin from autoAb (random, cannot predict when)
How to diagnose reactive hypogly due to autoimmune causes?
- Antibodies
2. Extended OGTT (up to 3h, sudden drop in BG)
Pathogenesis of alcohol related hypogly?
- reduced gluconeogenesis
- fasting (reduced food intake during binge drinking)
- and reactive (during re-feeding)
How to diagnose alcohol-related hypogly?
increased ketones
Cause of primary adrenal insufficiency?
Baseline ACTH and cortisol level after stimulation?
Addison’s disease
- high ACTH
- low cortisol, no increase
Cause of secondary adrenal insufficiency?
Baseline ACTH and cortisol level after stimulation?
Pituitary disease/ hypothalamic disease
- low ACTH (undetectable)
- sluggish response in cortisol level after stimulation
Describe the glucagon stimulation test.
What are the expected results? (2)
- Induce hyperglycemia (thus reactive hypoglycemia) and stress > test both adrenocortical and GH-IGF axis.
- Cortisol during hypoglycemic attach should increase normally over 450 nmol/L
- GH during hypoglycemia attack: increase normally up to 20 ng/mL
What are the definitions of neonate hypoglycemia in full-term and preterm infants? (2)
Full term: plasma glucose <2 mmol/L
Preterm: plasma glucose <1.1 mmol/L
Neonate hypogly can be due to excessive glucose utilization or decreased glucose production.
List 2 examples for the former.
- Maternal diabetes (common): fetal hyperinsulinemia
2. Persistent hyperinsulinemia hypoglycemia of infancy (PHHI): congenital hyperinsulinemia due to an adenoma, etc (rare)
Neonate hypogly can be due to excessive glucose utilization or decreased glucose production.
Which of the following are reasons for the latter?
A. Sepsis
B. Severe liver damage like acute hepatitis
C. Pre-maturity
D. Congenital adrenal hyperplasia (CAH)/ GH deficiency
E. Glycogen storage disease
All of the above
E: inborn errors of metabolism
Insulinoma may be part of multiple endocrine neoplasia MEN type?
type 1
For laboratory investivations of hypoglycemia, blood is collected in __________ tube during?
fluoride tube (gray tube) during symptoms of hypoglycemia
Hypoglycemia: Increased serum insulin and C-peptide, ddx?
Insulinoma, oral hypoglycemic
Hypoglycemia: increased serum insulin, decreased C-peptide, ddx?
exogenous insulin
