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Year 3 > Case 16 - Obesity/GCC/ADH dysfunction > Flashcards

Case 16 - Obesity/GCC/ADH dysfunction Flashcards

1
Q

What is Cushings?

A

Too many GCC in the body
Causes an over-activation of the fight or flight mechanism
Zona fasicularis is where GCC are produced in the adrenal cortex

50% 5y survival if left untreated

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2
Q

How can Cushings arise?

A

Iatrogenic - LT courses of steroids can reduce endogenous steroid production

ACTH-independent Cushings - where the problem is the adrenal glands and there is high GCC production in the absence of ACTH

ACTH-dependent - where the problem is higher up in the HPA axis
Hypothalamus makes CRH > pituitary makes ACTH > adrenal gland releases GCC
If there is a pituitary tumour for example, will produce excess ACTH and therefore more GCC will be produced
Ectopic tumours can do the same

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3
Q

Signs and symptoms of Cushings

A 
Truncal obesity (central)
Moonface
Humpback
Recent rapid weight gain
HTN
Myopathy
Glycosuria
Flushing of the face
Striae
Decreased libido
Depression
Hirsuitism
Bruising
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4
Q

Who should be tested for Cushings?

A 
Pituitary adenomas
Adrenal adenomas
PCOS
Multiple or progressive Sx
Features unusual for age e.g. HTN/osteoperosis
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5
Q

What tests can be done for Cushings?

A

Overnight 1 mg dexamethosone suppression test
Urinary free cortisol
Late night salivary cortisol
48 hour 2mg dexamethosone suppression test

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6
Q

What is late night salivary cortisol?

A

More accurate than random plasma testing
Should be done twice to confirm reading - done in the community, quick, cheap and non-invasive
If result is positive should do overnight dexamethosone suppression testing to confirm
Diurnal variation in cortisol will be lost in Cushings patients
Higher level than normal will be seen in Cushings
Reacts with prednisolone and cortisol

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7
Q

What is the overnight dexamethosone suppression test?

A

1mg dexomethosone given before bed, done in the community
Have BT the next morning - in normal patients, the cortisol will be suppressed in the morning due to negative ACTH feedback
In Cushing’s patients, the early morning rise in cortisol will still be seen

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8
Q

What is urinary free cortisol testing?

A

Over 24 hours, collect all urine and measure the cortisol found in the urine
Overall total of cortisol will be higher than normal patients
May have false positive in PCOS, depression and obesity

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9
Q

What is 48 hour dexamethosone suppression testing?

A

2mg dexamethosone used - 0.5mg taken every 6 hours

BT are done on day 0 and 2 to confirm rise in cortisol despite negative feedback

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10
Q

What physiological causes of Cushings should be tested for?

A 
Pregnancy
Stress
Malnutrition
Alcoholism
Depression
Morbidly obese
Metabolic syndrome
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11
Q

What tests can be done to find the aetiology of Cushings?

A 
Morning ACTH plasma level testing 
High dose dexamethosone suppression testing
IPSS 
MRI head
CT TAP
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12
Q

What is morning ACTH plasma level testing

A

If the patient has low ACTH, shows that the Cushings is ACTH-independent
Image adrenals to look for pathology

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13
Q

What is next if you have unsuppressed ACTH levels on testing?

A

With normal or raised ACTH levels, MRI head to look for pituitary adenoma
High dose dex suppression testing will inhibit ACTH production in pituitary tumours but not in ectopic or adrenal tumours

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14
Q

What is IPSS re Cushings?

A

For indeterminate MRI lesions, would perform inferior petrosal sinus sampling
This can detect type of ACTH-dependent Cushings

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15
Q

What happens if you have a negative IPSS in Cushings?

A

Ectopic source of ACTH

Should perform a CT TAP

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16
Q

How can you treat Cushings?

A

Metyrapone inhibits teh production of cortisol
This may be useful for preparation for surgery, but not in the LT
Surgery
Radiotherapy (often after surgery)

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17
Q

What types of adrenal tumours are there?

A

Phaechromocytoma - tumour of the medulla > increased catecholamine production

Carcinoma of the cortex - with symptoms relating to the zona affected and therefore the hormone that is being over-produced

18
Q

What types of pituitary tumours are there?

A

Non-functioning adenoma - slow-growing and symptoms solely related to mass effect e.g. compression of the optic nerve

Prolactinoma - actively produces prolactin leading to menorrhagia, galactorrhea, amenorrhea

FUnctioning adenoma - produces hormones
ie. ACTH-secreting tumours
GH-secretign tumours

19
Q

What is Addisons?

A

Lack of GCC production by the zona fasicularis in the cortex of the adrenal gland
Hypotension and hyponatraemia

20
Q

Signs and symptoms of Addisons?

A 
Weight loss
Low BP - often postural drop
Fatigue
Abdo pain
Hyperpigmentation (due to increased ACTH deposition)
Aches and pain
21
Q

What investigations for Addisons are done?

A

Can use random cortisol and ACTH
Short synacthen test (contra in recent pit gland bleeds) - should have decreased cortisol after stimulation
Can use insulin tolerance test - risky

22
Q

What is the treatment for Addisons?

A

Primary adrenal disease - LT steroids and aldosterone
Pituitary disease - LT steroids
Should taper up until asymptomatic
Wear a steroid bracelet
Carry a steroid card
Increase requirements when ill, playing sport etc.

Pred and dexamethosone are long-acting so OD
Hydrocortisone can be given BD (lower dose in the evening)

23
Q

What are the complications of Addisons treatment?

A

Under or over replacement
Over replacement, will leads to signs and symptoms of Cushings and osteoperosis
Under replacement will not resolve the symptoms - weight loss, hyponatraemia

24
Q

What is an Addisonian crisis?

A 
When GCC are very low
Leading to almost no fight-flight mechanism
DNV
Tachypnoeic
Dehydrated
Clammy
Reduced consciousness

Should treat with IV hydrocortisone 100mg and fluids
Glucose and dextrose

25
Q

What do you need to do when examining and taking a history for obesity?

A

How long weight was gained over and how much
Pattern of weight distribution
BP
Dip urine

26
Q

How do you classify obesity?

A

Using BMI and Wast circumference

BMI
<18.5 Underweight
18.5-24.9 Normal
25-29.9 Overweight
30-34.9 Obese I
35-39.9 Obese II
40+ Morbidly obese (obese III)

Waist circumference
Male = <94|94-102|>102 cm
Female = <80|80-88|>88 cm

27
Q

What are obesity interventions?

A

Should encourage lifestyle changes first e.g. diet, exercise and alcohol modification

28
Q

When should someone be referred to a tier 3 service?

A

Considering surgery
Drugs unsuccessful
Complex and can’t be managed in tier 2 services
Specialist interventions needed
Underlying cause of obesity needs to be investigated

29
Q

What drugs can be used for obesity?

A

Orlistat = Lipase
Helps to break down the fat so that it can be more easily excreted
Will have oily, foul smelling stools
Continue after 3 months only if patient has lost 5% of body weight
BMI 30+ or 28+ with RFs

30
Q

When is surgery for obesity indicated?

A

BMI over 40
BMI over 35 and other psychological or physical comorbidities that would benefit from losing weight
When all other interventions have not resulted in significant or maintained weight loss
If patient promises to adhere to strict lifestyle changes post-surgery
Can be gastric banding/sleeve/bypass

31
Q

What is the physiology of ADH?

A

ADH produced by the posterior pituitary gland in response to signals form teh hypothalamus
ADH inserts aquaporins in the collecting ducts of the kidney
Encourages more water reabsorption and boost BP by doing so

32
Q

What is diabetes insipidus?

A

When the posterior pituitary gland does not produce enough ADH or kidney becomes insensitive to ADH
Leads to polyuria and polydipsia

33
Q

How do you test for diabetes insipidus?

A

Do a water restriction test
Will become hypernatraemic and dehydrated
Decreased urine osmolality, increased serum osmolality

34
Q

How do you treat diabetes insipidus?

A

Replace with DDAVP

Correct hypernatraemia

35
Q

When can hypernatraemia occur?

A

When extremely dehydrated - due to desert, or due to people with cognitive disabilities etc. not remembering to drink, on ICU

36
Q

What can cause SIADH?

A

Small cell lung cancer, pneumonia
Brain tumour, head injury
Drugs e.g. SSRIs, carbemazepine

37
Q

How do you treat SIADH?

A

Try to treat the underlying cause if there is one
Salt administration, fluid restriction
Tolvaptan in chronic

38
Q

How do you diagnose SIADH?

A

Urine vs plasma osmolality

The urine osmolality will be more than in the plasma, due to increased resorption of water

39
Q

How do you exclude pseudohyponatraemia?

A

Re-test and do urine vs plasma osmolality, pseudohyponatraemia will have a normal plasma osmolality when it should be low - due to increased presence of other ions that there is an apparent hyponatraemia

40
Q

What are the signs and symptoms of hyponatraemia?

A 
Headache
Dizziness
Nausea
Coma
Signs of fluid overload
Signs if fluid underload
41
Q

How do you determine the cause of hyponatraemia?

A

If patient is dehydrated, is urine sodium higher than 20?
If yes - due to renal sodium loss, Addisons
If no - elsewhere loss due to diarrhoea, burns etc

If not dehydrated, oedematous?
If yes, nephrotic syndrome, CCF, liver failure
If no, is urine osmolality high?
Yes=SIADH
No= water overload, hypothyroidism

Year 3 (23 decks)

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