Endocrinology Flashcards
1
Q
Define Endocrinology
A
Study of hormones (and their gland of origin), their receptors, the intracellular signalling pathways, and their associated disease
2
Q
Define endocrine
A
Glands ‘pour’ secretions directly into blood stream (are ductless)
3
Q
Define exocrine
A
(outside) - glands pour secretions through a duct to site of action
4
Q
Define autocrine
A
Feedback on the same cell that secreted the hormone
5
Q
4 main differences between water and fat soluble hormones
A
Water-soluble
- Transport: Unbound
- Cell interaction: bind to surface receptor
- Half-life: short
- Clearance:fast
Fat-soluble
- Transport: Protein bound
- Cell interaction: diffuse into cell
- Half-life: long
- Clearance: slow
6
Q
4 hormone classes
A
- Peptides
- Amines
- Iodothyronines
- Cholesterol derivatives & steroids
7
Q
Example of a peptide hormone
A
Insulin
8
Q
3 characteristic features of peptide hormones
A
- Stored in secretory granules
- Released in pulses or bursts
- Cleared by tissue or circulating enzymes
9
Q
2 example of amine hormones
A
Adrenaline & noradrenaline
10
Q
When noradrenaline & adrenaline are broken down, what is formed & why is this important?
A
Normetanephrine & metanephrine
Have longer half lives & so can be measured in serum
Act as indicators of noradrenaline & adrenaline activity
11
Q
5 methods of controlling hormone action
A
- Hormone metabolism
- Hormone receptor induction
- Hormone receptor down regulation
- Synergism
- Antagonism
12
Q
Define appetite
A
Desire to eat
13
Q
Define hunger
A
Need to eat
14
Q
Define anorexia
A
Lack of appetite (desire to eat)
15
Q
What body structure controls eating?
A
Hypothalamus
16
Q
Where is the hunger centre?
A
Lateral hypothalamus
17
Q
Where is the satiety centre?
A
Ventromedial hypothalamic nucleus
18
Q
Role of leptin
A
Switches off appetite
19
Q
Role of peptide YY in appetite
A
Inhibits gastric motility
Reduces appetite
20
Q
Role of CCK in appetite
A
Delays gastric emptying
Gall bladder contraction
Insulin release
21
Q
Role of ghrelin in appetite
A
Stimulates GH release
Stimulates appetite
22
Q
When is PTH secreted?
A
It increases the absorption of Ca2+ and is secreted when Ca2+ levels fall.
23
Q
Causes of hypercalcaemia
A
- Malignancy
- Bone mets, myeloma, PTHrP - PTH related peptide (acts like PTH, but isn’t PTH), lymphoma
- Primary hyperparathyroidism
- Thiazides
- Thyrotoxocosis
- Sarcoidosis
24
Q
Symptoms of hypercalcaemia
A
- Thirst
- Nausea
- Constipation
- Confusion → coma
- Renal stones
- ECG abnormalities
- short QT
25
Causes of hypocalcaemia
Osteomalacia
- Caused by vit D deficiency
26
Action of PTH in terms of phosphate?
PTH acts to push phosphate out of the kidneys
(reduces reabsorption at PCT)
27
2 categories of insulin
Basal insulin
Prandial/meal-time insulin
28
What are the 2 main differences between basal & prandial insulins?
Basal
* Work over a period of time
* Cover the period between meals
Prandial
* Rapid acting
* Given with a meal
29
Advantages of giving basal insulin to a patient with T2 diabetes mellitus?
Simple for patients to adjust themselves based on fasting
Carries on with oral therapy
Less risk of hypoglycaemia at night
30
Disadvantages of giving basal insulin to a patient with T2 diabetes mellitus?
Doesn't cover meals
Best used with long-acting insulin analogues which are considered expensive
31
Advantages of giving pre-mixed insulin to a patient with T2 diabetes mellitus?
Both basal & prandial components in one preparation
Can cover insulin requirements through most of the day
32
Disadvantages of giving pre-mixed insulin to a patient with T2 diabetes mellitus?
Not physiological
Requires constant meal & exercise pattern
Increased risk for nocturnal hypoglycaemia
Increased risk for fasting hyperglycaemia if basal component doesn't last long enough
33
Describe the blood supply to the anterior pituitary gland
Receives no arterial blood supply
Receives blood through portal venous circulation from the hypothalamus
34
Describe the 4 stages of the pituitary-thyroid axis
1. Hypothalamus secretes TRH
2. Stimulates pituitary to secrete TSH
3. Stimulates thyroid to secrete T4&T3
4. T4&T3 inhibit the hypothalamus & pituitary
35
What will happen to TSH levels if you do not have a thyroid?
TSH will increase
(no T4&T3 produced so hypothalamus & pituitary not inhibited)
36
In the menopause, the ovaries fail. What will happen to levels of oestrogen, LH & FSH?
Oestrogen decreases
LH & FSH increase
37
3 main problems caused by pituitary disease
- Pressure on local structure, eg optic nerve
- Pressure on normal pituitary → hypopituitarism
- Functioning tumour → eg prolactinoma
38
How does a meningioma usually present?
Loss of VA
Endocrine dysfunction
Visual field defects
39
What is lymphocytic hypophysitis?
Inflammation of the pituitary gland due to an autoimmune reaction
40
What is important to measure when testing the pituitary-thyroid axis?
Ft4
| (free T4)
41
If you have a primary hypothyroidism, what would you expect the levels of TSH & Ft4 to be like?
Raised TSH
Low Ft4
(primary = problem in the thyroid)
42
If you have a hypopituitarism, what would you expect the levels of TSH & Ft4 to be like?
Low Ft4
Normal or low TSH
43
What does Grave's disease result in?
Overproduction of thyroid hormones
44
If you have Grave's disease, what would you expect the levels of TSH & Ft4 to be like?
Low TSH
High Ft4
45
What is thyrotoxicosis?
The clinical manifestation of excess thyroid hormone action at the tissue level due to inappropriately high circulating thyroid hormone concentrations
46
Describe the half life of vasopressin & explain why this is relevant?
Short half life
Allows fine tuning of water levels
47
Which of the following is not under the control of the pituitary gland?
* Thyroid
* Adrenal cortex
* Adrenal medulla
* Testis
* Ovary
Adrenal medulla
48
Which of the following statements is false?
* The pituitary gland lies in the sella turcica
* The weight of the pituitary gland is around 0.5g
* ACTH is secreted from the pituitary during stress
* The pituitary regulates calcium metabolism
* The anterior and posterior pituitary are distinct on an MRI scan
The pituitary regulates calcium metabolism
(regulated by parathyroid)
49
In men all of the following are mainly produced in the adrenal cortex except...?
* DHEAS
* Testosterone
* Aldosterone
* 17-OH progesterone
* Androstenedione
Testosterone
50
Where is testosterone produced?
The testis
51
What is AVP?
Vasopressin
52
Which of the following regarding AVP is false?
* AVP levels have a linear relationship with serum osmolality
* Is produced in the pituitary gland
* Stimulates reabsorption of water in the collecting duct of the nephron
* In hypotension, baroreceptors predominantly activate ADH production & secretion
* Further AVP production is no longer effective once urine osmolality has reached a plateau
Is produced in the pituitary gland
(it is produced in the hypothalamus & stored in the posterior pituitary)
53
Where is growth hormone's main site of action to stimulate IGF1 release?
* Bone
* Liver
* Adrenal cortex
* Muscle
* Pancreas
Liver
54
Hypothalamic hormones act to mainly stimulate the release of all these hormones except
* ACTH
* GH
* TSH
* Proalctin
* LH
Prolactin
| (dopamine inhibits prolactin)
55
The following are typical features of excess GH secretion except?
* Polyuria
* Joint pains
* Sweating
* Hypotension
* Headaches
Hypotension
| (high bp is common)
56
The following hormones all have a circadian rhythm except?
* Cortisol
* Testosterone
* DHEA
* 17OH progesterone
* Thyroxine (T4)
Thyroxine
57
Typical features of cortisol deficiency include the following except?
* Hypotension
* Muscle aches
* Weight loss
* Hyperglycaemia
* Lethargy
Hyperglycaemia
58
Effect of cortisol on blood glucose
Cortisol = stress hormone
Makes blood glucose rise
59
A 38 year old lady presented with weight gain, menorrhagia (heavy periods) and constipation. She is most likely suffering from?
* Cushing's syndrome
* Addison's disease
* Primary hypothyroidism
* Graves disease
* Acromegaly
Primary hypothyroidism
60
What causes Cushing's syndrome?
Levels of cortisol in the body are too high
61
What causes the symptoms of Addison's disease?
The adrenal gland is damaged in Addison's disease, so it does not produce enough cortisol or aldosterone.
62
What is Graves disease also known as?
Hyperthyroidism
63
Which test would you likely want to perform in a patient with proximal muscle weakness, purple striae and thin skin?
* Synacthen test
* Overnight dexamethasone suppression test
* Insulin tolerance test
* Glucagon test
* Skin allergy tests
Overnight dexamethasone suppression test
64
What is dexamethasone suppression test used to diagnose
**Cushing's syndrome (excess cortisol)**
## Footnote
Normally, when the pituitary gland makes less ACTH, the adrenal glands make less cortisol.
Dexamethasone, which is like cortisol, lowers the amount of ACTH released by the pituitary gland. This in turn lowers the amount of cortisol released by the adrenal glands.
After a dose of dexamethasone, cortisol levels often stay very high in people who have Cushing's syndrome.
65
What is the synacthen test used to diagnose?
Addison's disease
66
How does the Synacthen test work?
During the synacthen test you are given a chemical called tetracosactide (synacthen is the commercial name of this chemical). Tetracosactide is a chemical copy of ACTH.
ACTH is the hormone released by your pituitary gland, which stimulates the adrenals to produce cortisol. If the adrenal glands are working properly they should respond to the tetracosactide by producing cortisol. Levels of cortisol are checked by taking a blood sample.
If levels of cortisol remain low, despite the tetracosactide injection, this suggests there is a problem with the function of the adrenal glands (ADDISON'S)
67
What is the insulin tolerance test (ITT) used for?
The ITT is used to test how much ACTH and cortisol you can produce and how much growth hormone is available when your body is stressed.
The ‘stress’ in the test is low blood sugar. This is caused by an injection of insulin, under very controlled conditions.
68
A 24 year old girl presented with hirsutism, oligomenorrhoea and acne. What test would you likely carry out from the ones below?
* Ultra sound adrenals
* Ultra sound ovaries
* MRI ovaries
* CT scan adrenals
* Prolactin
(oligomenorrhoea = infrequent periods. Hirsutism = excess hair most often noticeable around the mouth and chin. )
**Ultra sound ovaries**
(these are typical presenting features of PCOS)
69
A 54 year old gentleman presented with hyponatraemia.
All the following conditions need excluding before confirming SIADH except?
* Hypothyroidism
* Hypervolaemia
* Euvolaemia
* Adrenal insufficiency
* Diuretic use
Euvolaemia (= normal amount of body fluids)
(SIADH = excess ADH)
70
Normal serum sodium levels?
135-144mmol/L
71
A 66 year old gentleman had a serum sodium of 124 mmol/l, serum osmolality 265 mmol/l and a urine sodium of 52 mmol/l. What would you like to perform first?
* Chest X-ray
* CT brain
* Skin turgor and jugular venous pressure test
* Thyroid function test
* Synacthen test
Skin turgor and jugular venous pressure test
(needed to diagnose SIADH)
72
5 Essential criteria for diagnosis of SIADH
* Hyponatraemia
* Plasma hypo-osmolality
* Urine osmolality \> 100 mOsm/Kg
* Clinical euvolaemia
* Increased urinary sodium excretion (\>30mmol/L with normal salt and water intake)
73
How can you diagnose clinical euvolaemia
No clinical signs of hypovolaemia (decreases in BP, tachycardia, decreased skin turgor, dry mucous membranes)
No clinical signs of hypervolaemia (oedema, ascites)
74
The following are most likely causes of SIADH except?
* MS
* Lung abscess
* Subdural haemorrhage
* Lymphoma
* Cerebrovascular accident
MS
75
A 28 year old presented with a microprolactinoma. What is the most **un**likely symptom?
* Galactorrhoea
* Oligomenorrhoea
* Decreased sexual appetite
* Headaches
* Visual field defects
Visual field defects
76
The following suppress appetite except?
* Peptide YY
* Ghrelin
* CCK
* GLP1
* Glucose
Ghrelin
77
The main adipose signal to the brain is
* CCK
* Neuropeptide Y
* Leptin
* Agouti-related peptide
* Adiponectin
Leptin
78
A 65 year old lady is diagnosed with SIADH. Her sodium is 123mmol/l. What is your first line of management?
* If symptomatic, treat with fluid restriction
* If she is asymptomatic I will treat with hypertonic saline
* If she is asymptomatic I will treat with fluid restriction
* If she is asymptomatic I will repeat the sodium level the next day
* If she is asymptomatic I will give normal saline
If she is asymptomatic I will treat with fluid restriction
79
A patient with Addison's disease presents with a chest infection. What do you do?
* Omit his steroids to avoid immunosuppression
* Stop his steroids as they have precipitated a chest infection
* Double his steroid dose whilst unwell
* Keep him on his usual steroid dose
* None of the above
Double steroid use whilst unwell
80
Define primary, secondary and tertiary hypogonadism
Primary hypogonadism - problem with gonad
Secondary - problem with pituitary
Tertiary - problem with hypothalamus
81
Describe LH & testosterone levels which are typical of secondary hypogonadism?
(problem with pituitary)
Low LH & ∴ low testosterone
82
Typical features of hypogonadism in a male include the following except?
* Decreased sweating
* Joint & muscular aches
* Decreased sexual appetite
* Decreased hair growth
* Asymptomatic
Hypogonadism → low testosterone
Decreased sweating
83
A patient has a noon testosterone level below the normal range. What will you do?
* Treat with testosterone gel
* Repeat the test at 0900h and check for symptoms
* Repeat the test at noon to keep things equal
* Refer to endocrinology
* Ignore it
Repeat the test at 0900h and check for symptoms
84
The first line treatment for a patient with a symptomatic prolactinoma is usually:
* Radiotherapy
* Transphenoidal surgery
* Dopamine agonists
* Transfrontal surgery
* Somatostatin analogues
Dopamine agonist
dopamine inhibits prolactin
85
Typical visual field defect of a patient with a large pituitary mass is?
* Unilateral quadrantanopia
* Bitemporal hemianopia
* Complete unilateral visual field loss
* Complete bilateral visual field loss
* None of the above
Bitemporal hemianopia
86
Satiety is...
The physiological feeling of no hunger
87
The centres of appetite regulation in the brain are mainly found in the...
Hypothalamus
88
What does MODY stand for?
Maturity onset diabetes of the young
89
Describe MODY
A rare form of diabetes which is different from both T1&T2 DM
It runs strongly in families & is caused by a mutation in a single gene
90
4 clinical signs a patient has MODY?
* Parents affected with diabetes
* Absence of islet autoantibodies
* Evidence of non-insulin dependence
* Good control of low dose insulin
* No ketosis
* Measurable C-peptide
* Sensitive to sulphonylurea
91
Cause of Addison's disease
Destruction of the adrenal gland - autoimmune
92
Cause of secondary adrenal insufficiency
No stimulation of the adrenal gland due to hypopituitarism
93
Define hyperosmolar hyperglycaemic state (HHS)
Characterised by profound hyperglycaemia, hyperosmolality and volume depletion in the absence of significant ketoacidosis
A serious complication of diabetes
94
Most common presentation of thyroid cancer
An asymptomatic thyroid nodule
95
Risk factors for thyroid cancer
Head & neck irradiation
Female
Family history
96
Most important diagnostic test for thyroid cancer
Fine-needle aspiration
97
Treatment for thyroid cancer
Usually total thyroidectomy
98
What is the difference between Cushing's syndrome & disease?
Cushing's disease is a specific type of Cushing's syndrome
When a pituitary tumour makes too much cortisol
