Exam 4 - Hypoglycemia Flashcards
what are some examples of how lab error can cause hypoglycemia?
bg is lowered if the sample sits before being spun
bg is lowered by very high white cell counts or red cell mass
hand held glucometers are less reliable if red cell count is out of reference range (overestimates bg in anemic animals or underestimates bg if PCV >55%)
what are the two general mechanisms that cause hypoglycemia that we care about?
decreased glucose production
excessive glucose utilization
what animals are commonly affected by decreased glucose production?
puppies
prolonged starvation
impaired hepatic gluconeogenesis - PSS, end stage liver failure, hepatic enzyme deficiencies
decreased glucose counter-regulatory hormones - cortisol deficiency (addison’s)
what animals are commonly affected by excessive glucose utilization causing hypoglycemia?
increased insulin/insulin-like substance - insulinomas, other tumors (hepatocellular carcinoma, hemangiosarcoma)
insulin overdose
xylitol ingestion - triggers insulin secretion in dogs
sepsis
what are the clinical signs & findings associated with hypoglycemic disorders?
determined by both the absolute bg & rate of decline - chronic hypoglycemia is very well tolerated
weakness, tremors, & collapse
depressed neurologic states or seizures
if the cause of hypoglycemia isn’t evident on physical exam or routine labs, what diagnostics may you pursue?
hepatic function tests - bile acids to rule out PSS
acth stim - rule out atypical addison’s
insulin - need to measure concurrent bg & look at insulin to glucose ratio
imaging - ultrasound is the test of choice!!! will identify large non-pancreatic masses, may miss pancreatic islet cell tumors as they are often small, but may identify metastatic disease, & useful for screening for hepatic disorders
how is karo syrup used for emergency management of hypoglycemia?
rub > 0.1 ml/kg on the gums - good plan while trying to get iv access
how is a dextrose bolus used for emergency management of hypoglycemia?
0.25 ml/kg IV of 50% dextrose will increase bg by about 50 mg/dl - need to dilute with concurrent fluids, or 3 parts sterile water (make a 12.5% solution)
may need to repeat - depending on underlying cause
bolus may trigger more release of insulin from an insulinoma
what are some clues of insulinomas in patients?
dogs often gain weight
appetite can be decreased (as insulin is an appetite suppressant)
what is the general background on insulinomas?
tumor arising from pancreatic beta cells - uncommon disorder occurring in middle aged to older dogs (very rare in cats)
insulin secretion can be episodic - patient may be euglycemic in between collapse events, so you may need to fast the dog to trigger hypoglycemia
predictably malignant - mets occur early in disease
where do insulinomas commonly met to?
lungs, liver, lymph nodes
how are insulinomas diagnosed?
measurement of insulin during a period of hypoglycemia (bg <60 mg/dl)
insulin may be above reference range or in the upper half
imaging - ultrasound may miss small lesion, tumors are often <4cm & isoechoic to the pancreas
how is diet a part of treatment for hypoglycemic patients?
frequent small meals - complex carbs may be useful
how is surgery used for treating hypoglycemia from an insulinoma?
surgical removal or debulking - true surgical cure is unlikely, but even incomplete removal can be very helpful
patients live longer if you can get a substantial chunk of the tumor out - recommend surgery even if gross metastatic disease is noted
how are glucocorticoids used to treat insulinomas causing hypoglycemia?
used to antagonize the effects of insulin - use the lowest necessary dose, start at 0.5 mg/kg SID & increase as needed
