Pituitary Flashcards
(59 cards)
1
Q
What is the final common pathway by which signals from multiple signals can reach the anterior pituitary?
A
Hypothalamus
2
Q
What is the hypothalamus regulated by?
A
- Hormone mediated signals (negative feedback)
- Neural inputs
3
Q
What non-endocrine functions is the hypothalamus also involved in?
A
- Temperature regulation
- Food intake
- Thirst
4
Q
6 hormones released by hypothalamus affecting anterior pituitary
A
- Growth hormone releasing hormone (GHRH)
- Somatostatin (inhibitory)
- Gonadotropin releasing hormone (GnRH)
- Corticotropin releasing hormone (CRH)
- Thyrotropin releasing hormone (TRH)
- Dopamine (inhibitory)
5
Q
What hormone(s) does GHRH trigger release of?
A
Growth hormone (GH)
6
Q
What hormone(s) does somatostatin inhibit release of?
A
Growth hormone (GH)
7
Q
What hormone(s) does GnRH trigger release of?
A
- Follicle stimulating hormone (FSH)
- Luteinising hormone (LH)
8
Q
What hormone(s) does CRH trigger release of?
A
Adrenocorticotrophic hormone (ACTH)
9
Q
What hormone(s) does TRH trigger release of?
A
Thyroid stimulating hormone (TSH)
10
Q
What hormone(s) does dopamine inhibit release of?
A
Prolactin
11
Q
What factor(s) is growth hormone stimulated by?
A
- Hypoglycaemia
- Exercise
- Sleep
12
Q
What factor(s) is/are growth hormone suppressed by?
A
Hyperglycaemia
13
Q
Effects of GH
A
- Linear growth in children
- Acquisition of bone mass
- Stimulates protein synthesis, lipolysis, glucose metabolism
- Regulation of body composition
- Psychological wellbeing
14
Q
Primary effects of FSH and LH
A
- Testosterone production in testes
- Estrogen production in ovaries
15
Q
Secondary effects of FSH and LH (males)
A
- Penis and scrotum growth
- Facial hair growth
- Larynx elongates (lowers voice)
- Shoulders broaden
- Body, armpit and pubic hair growth
- Musculature increases body-wide
16
Q
Secondary effects of FSH and LH (females)
A
- Breasts develop and mature
- Hips broaden
- Pubic hair grows
17
Q
What is prolactin essential for?
A
Lactation
18
Q
When do levels of prolactin increase?
A
Pregnancy and breast feeding
19
Q
How does prolactin inhibit gonadal activity?
A
Central suppression of GnRH (thus decreased FSH/LH levels)
20
Q
Effects of ADH
A
- Primary physiological determinant of the rate of free water excretion
- Augments the water permeability of the luminal membranes of cortical and medulla collecting tubes
21
Q
Major stimuli for ADH secretion
A
- Hyperosmality (high solute conc. in blood)
- Effective circulating volume depletion
22
Q
What does oxytocin stimulate?
A
Contraction of smooth muscle of breast and uterus
23
Q
What does oxytocin have roles in?
A
- Milk ejection reflex
- Parturition (birth)
24
Q
Major causes of hypopituitarism
A
- Pituitary/parapituitary tumours
- Radiotherapy
- Pituitary infarction (apoplexy)
- Infiltration of the pituitary
- Trauma
- Isolated hypothalamic releasing hormone deficiency
25
Manifestations of GH deficiency
- Children
> Poor growth
- Adults
> Increased abdominal fat
> Decreased lean body mass
> Impaired lipid profile
> Decreased muscle strength and exercise capacity
> Impaired cardiac function
> Decreased bone mineral density
> Impaired psychological wellbeing
26
How is GH deficiency diagnosed?
GH stimulation tests
27
How is GH deficiency treated?
Hormone replacement
28
Manifestations of FSH/LH deficiency
- Children
> Delayed puberty
- Men
> Decreased libido
> Infertility
> Decreased secondary sex features
> Decreased muscle mass and strength
> Decreased mood and wellbeing
> Osteoporosis
> Anaemia
- Women
> Decreased libido
> Menstrual disorders
> Infertility
> Dyspareunia
> Osteoporosis
> Premature atherosclerosis
29
How is FSH/LH deficiency diagnosed?
- Measure FSH, LH and oestradiol levels and take menstrual history (female)
- Measure FSH, LH and morning testosterone levels (male)
30
How is FSH/LH deficiency treated?
Hormone replacement
31
Manifestations of ACTH deficiency
- Fatigue
- Weakness
- Nausea/vomiting
- Anorexia
- Weight loss
- Hypoglycaemia
- Hypotension
- Anaemia
32
How is ACTH deficiency diagnosed?
- 9am serum cortisol and ACTH levels
- Dynamic tests:
> Short Synacthen test
> Insulin tolerance test
> Glucagon test
33
How is ACTH deficiency treated?
- Replace what is missing
- Approximate natural rhythm
34
Manifestations of TSH deficiency
- Fatigue
- Weakness
- Cold intolerance
- Bradycardia
- Inability to lose weight
- Puffiness
- Pale and dry skin
- Constipation
35
How is TSH deficiency diagnosed?
Measure TSH, fT4 and fT3 levels
36
How is TSH deficiency treated?
Hormone replacement
37
What is central diabetes insipidus?
Deficient secretion of ADH
38
Causes of central diabetes
- Idiopathic (autoimmune destruction of hormone secreting cells)
- Tumours
- Neurosurgery or trauma
- Infiltrative disorders
- Infections
- Hypoxic encephalopathy or severe ischaemia
39
Manifestations of ADH deficiency
- Polyuria of dilute urine
- Polydipsia
- Nocturia
40
Major causes of polyuria
- DM
- Renal failure
- Primary polydipsia
- Diabetes insipidus
41
How is ADH deficiency diagnosed?
- Urine output
- Osmolalities (plasma, urine)
- Blood electrolytes/glucose/urea/creatinine
- Water deprivation test
42
How is ADH deficiency treated?
ADH analogues
43
What is acromegaly?
Hypersecretion of GH
44
How is acromegaly diagnosed?
- Oral glucose tolerance test
- IGF-I
- Pituitary imaging
45
How is acromegaly treated?
- Pituitary surgery
- Dopamine agonists
- Somatostatin analogues
- GH receptor antagonists
- Radiotherapy
46
What is prolactinoma?
Non-cancerous tumour of pituitary causing too much prolactin
47
Manifestations of prolactinoma
- Hypogonadism
- Galactorrhoea
- Mass effects
48
How is prolactinoma diagnosed?
- Exclude other causes of high prolactin
- Pituitary imaging
49
How is prolactinoma treated?
- Dopamine agonists
- Surgery
- Radiotherapy
50
What is Cushing's Syndrome?
Cortisol hypersecretion
51
How is Cushing's diagnosed?
- 24h UFC
- Midnight serum or salivary cortisol levels
- Overnight or low dose dexamethazone suppression test
52
How is Cushing's treated?
- Pituitary surgery
- Radiotherapy
- Drugs
- Bilateral adrenalectomy
53
What is a TSHoma/FSHoma?
Pituitary tumour causes TSH/FSH hypersecretion
54
Manifestations of TSHoma
- Thyrotoxicosis (hyperthyroidism)
- Mass effects
55
How is TSHoma diagnosed?
- Hormonal tests by experts
- Pituitary imaging
56
How is TSHoma treated?
- Surgery
- Medications
- Radiotherapy
57
Manifestations of FSHoma
- Menstrual irregularities
- Ovarian hyperstimulation
- Testicular enlargement
- Infertility
- Mass effects
58
How is FSHoma diagnosed?
- Hormonal tests by experts
- Pituitary imaging
59
How is FSHoma treated?
- Surgery
- Radiotherapy
