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Pathology > C - Hypoglycaemia > Flashcards

C - Hypoglycaemia Flashcards

1
Q

what key factor does treatment of hypoglycaemia depend on

A

whether pt is conscious or not

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2
Q

Mx of hypoglycaemia for alert and orientated pt

A

oral carbs
rapid acting: juice / sweets
longer acting: sandwich

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3
Q

Mx of hypoglycaemia for drowsy / confused with a good swallow pt

A

buccal glucose
rapid acting: eg hypostop / glucogel
longer acting: IV access ?

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4
Q

Mx of hypoglycaemia for unconscious pt or poor swallow pt

A

IV access
20% glucose IV

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5
Q

Mx of hypoglycaemia if deteriorating / refractory / insulin induced / difficult IV access

A

IM / SC img glucagon

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6
Q

what must be simultaneously done when Tx hypo

A

continuous monitoring
- keep rechecking the glucose

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7
Q

what can extravasation of glucose cause

A

irritation and phelbitis

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8
Q

how long does glucagon take to work and why

A

15-20 mins
mobilised glycogen stores

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9
Q

what is the danger of using glucagon

A

rebound hypoglycaemia

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10
Q

who can’t be given glucagon and why

A

liver failure pts
- no glycogen stores to mobilise

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11
Q

define hypoglycaemia in terms of glucose level

A

hard to say
- on wards: BM below 4 mmol/L
- sometimes below 3.5

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12
Q

what is a worrying blood sugar in a neonate

A

2.5

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13
Q

symptoms of hypoglycaemia

A

can be none
adrenergic: tremor, palpitations, sweating, hungry
neuroglycopaenic: somnolence, confusiom, incoordination, seizures, coma

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14
Q

what is it called when you get no symptoms of hypoglycaemia

A

loss of hypoglycaemia awareness

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15
Q

who gets loss of hypoglycaemia awareness

A

people who are having frequent hypos (insulin T1DM)

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16
Q

what 3 factors define hypoglycaemia

A

low glucose
symptoms
relief of symptoms with glucose administration

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17
Q

what is the first physiological response to low glucose

A

pancreas stops making insulin & starts making glucagon

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18
Q

what is the effect of the body reducing insulin and producing glucagon in response to low glucose

A

reduced peripheral uptake of glucose
increased glycogenolysis
increased gluconeogenesis
increased lipolysis

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19
Q

where is glycogen stored

A

liver

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20
Q

what is glycogen

A

store of glucose

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21
Q

what is gluconeogenesis

A

production of glucose from amino acids

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22
Q

how are ketones produced in response to low glucose

A

low glucose
–> reduced insulin production and increased glucagon production in pancreas
–> increased lipolysis
–> increased free fatty acids
–> beta oxidation (ATP generation from burning FFAs in mitochondria)
–> increased ketone body production

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23
Q

are ketones formed when even small amounts of insulin are circulating

A

NO - only formed when insulin suppressed

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24
Q

what is a later response of the body to low glucose

A

low neuronal glucose sensed by hypothalamus
–> sympathetic activation producing catecholamines
also
–> ACTH, cortisol, GH production

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25
Q

how do you diagnose hypoglycaemia in healthy people

A

conduct a prolonged fast to demonstrate it

26
Q

gold standard way of measuring glucose

A

venous glucose

27
Q

why is cap blood glucose not as useful

A

measured in whole capillary blood with poor precision tools that aren’t quality controlled

28
Q

why is venous blood glucose gold standard

A

lab analysis with quality control
tube contains fluoride oxalate

29
Q

causes of hypo without DM

A

fasting / reactive
paeds vs adult
critically unwell
organ failure - renal / liver
hyperinsulism
post gastric bypass
drugs
extreme weight loss
factitious

30
Q

why does liver / kidnet failure give you hypos

A

liver - no stores of glycogen
kidney - no gluconeogenesis

31
Q

what is the leading cause of hypos in people with DM

A

mismatch between carbs eaten and meds taken

32
Q

other causes of hypos in DM

A

medications
inadequate carb intake / missed meal
impaired awareness of hypos
xs alcohol
strenuous exercise
AI conditions eg Addisons

33
Q

what drugs other than insulin causes hypos

A
  • sulphonylureas *
    meglitinides (not used as much)
    GLP 1 agonists with insulin
34
Q

what non DM drugs increase risk of hypos

A

beta blockers
alcohol

35
Q

what biochemical tests need to be done to determine cause of hypoglycaemia

A

insulin levels
c-peptide
drug screen
auto ABs
cortisol / GH
free fatty acids / blood ketones
lactate

36
Q

when should biochemical tests be done to determine cause of hypo in non DM pts

A

only when they’re having the hypo !! useless if they’re not

37
Q

what is C peptide

A

a marker of how much insulin the pancreas is making

38
Q

what is the use of measuring C peptide and not just insulin

A

insulin reading tells you how much insulin is in the blood
C peptide tells you how much of that insulin was made by the pancreas - ie excludes exogenous insulin from injections

39
Q

what are the 3 classifications of hypos based on insulin and C peptide

A

hypoinsulinaemic hypo (low insulin & CP)
hyperinsulinaemic hypo (high insulin & CP)
exogenous insulin (high insulin, low CP)

40
Q

what does hypoinsulinaemic hypo indicate

A

normal response to a hypo - ie hypo is not caused by faulty insulin production

41
Q

what does hyperinsulinaemic hypo indicate

A

hypo caused by too much insulin production

42
Q

what does exogenous insulin hypo indicate

A

likely factitious insulin injection to intentionally cause hypo in non DM pt
(this is also seen in DM pts, but you wouldn’t bother measuring insulin & CP as you assume it is due to exogenous insulin already)

43
Q

what causes of hypoglycaemia would have a hypoinsulinaemic hypo

A

all systemic causes
- starving / fasting
- exercise
- critically ill
- hypopituitarism / adrenal failure
- liver failure
- anorexia

44
Q

what type of hypo do neonates have

A

hypoinsulinaemic hypo (normal)

45
Q

why do neonates get hypoglycaemia

A

inadequate glycogen and fat stores

46
Q

risk factors for neonatal hypoglycaemia

A

premature
co-morbidities
IUGR
SGA
inborn metabolic defects

47
Q

give an example of an inborn metabolic defect that causes neonatal hypoglycaemia and the effect of this

A

fatty acid oxidation defect - no ketones produced but high fatty acids

48
Q

causes of hyperinsulinaemic hypoglycaemia

A

islet cell tumour - insulinoma
drugs eg insulin, sulphonylureas
islet cell hyperplasia
rare genetic forms of hyperinsulism
rare AI

49
Q

3 causes of islet cell hyperplasia

A

infant of diabetic mother
beckwith weidemann syndrome
nesidioblastosis

50
Q

what is the commonest cause of hyperinsulinaemic hypoglycaemia

A

drugs
the others are super rare

51
Q

Ix for hyperinsulinaemic hypoglycaemia due to ?insulinoma

A

glucose (low)
insulin (high)
c peptide (high)
sulphonylurea drug screen ( must be -‘ve to diagnose insulinoma)

52
Q

describe how insulin is secreted in pancreas

A

glucose enters beta cell
undergoes glycolysis via glucokinase
ATP and glucose-6-P is produced
ATP closes the K+ channel
K+ prevented from leaving cell, so depolarises membrane
Ca2+ influx
Preformed insulin in vesicles fuse with membrane and are released

53
Q

how do sulphonylureas work

A

they bind to the K+ channel (Sur 1 subunit) in beta islet cells and force it closed, irrespective of glucose level.
this causes membrane depolarisation and Ca influx which releases insulin from their vesicles

54
Q

prevalance of insulinoma

A

1-2 million per year

55
Q

when does hypoglycaemia occur in insulinoma

A

fasting only

56
Q

what % of insulinomas are malignant? associated with MEN1?

A

10% malignant
8% associated with MEN1

57
Q

Tx of insulinoma

A

resection

58
Q

what is the rare cause of low glucose/insulin/CP/FFA AND ketones?

A

non islet cell tumour hypoglycaemia
eg secrete big IGF2 (an insulin like factor that mimicks insulin)

59
Q

examples of non islet cell tumours causing hypos

A

mesenchymal tumours - mesotheliomas / fibroblastomas
epithelial carcinomas

60
Q

who gets reactive / post prandial hypos

A

post gastric bypass surgery
hereditary fructose intolerance
early / pre DM

61
Q

why do anorexics have hypos

A

poor glycogen stores in liver

Pathology (87 decks)

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